Substituted organofluoroborates as imaging agents

ABSTRACT

Fluoridated organofluoroborates comprising at least one  18 F atom and precursors thereto, for use in PET scanning.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the priority benefit of U.S. patent applicationNo. 61/775,280, the contents of which are incorporated herein byreference.

TECHNICAL FIELD

This invention relates to the field of ¹⁸F radiolabeled reagents for usein positron emission tomography (PET) imaging.

BACKGROUND

¹⁸F is the isotope of choice for many PET cancer imaging applications.

PET imaging agents are often based on a labeled biomolecule. Examplesinclude fluorodeoxyglucose (FDG); Octreotate, an octapeptide that isused to image cancer; and folate, which has been used to image cancer.Since the high energy particle bombardment used to produce ¹⁸F destroyscomplex organic molecules, ¹⁸F is first made as fluoride ion in acyclotron and subsequently attached to the biomolecule used as theimaging agent. Also, conditions used to incorporate ¹⁸F are often tooharsh for direct labeling of many biomolecules. Therefore, ¹⁸F isusually introduced into a precursor (such as an aryl fluoride) that isthen subsequently appended to a larger molecule. Such multi-stepprocedures result in delays, with consequent loss in specificradioactivity.

Some methodologies for incorporating ¹⁸F into imaging agents have beenreported, including a new approach which makes use of boron as anacceptor capable of binding several ¹⁸F atoms, thus increasing thedensity of positron emitters in the resulting imaging agent (see, forexample, PCT publication WO 2005/0077967). In addition, the use ofarylboronic acids/esters as ¹⁸F acceptors has been reported. Thisapproach has circumvented the previous practice of generating arylfluorides in multi-step procedures. ¹⁸F radiolabeled substitutedaryl-fluoroborates for use in PET imaging have also been reported (see,for example, WO 2009/012596).

SUMMARY

A consideration in the design of PET imaging agents is the longevity ofthe agent itself. It is desirable that the imaging agent be sufficientlystable with respect to loss of ¹⁸F ions (termed herein as ‘solvolyticde-18F-fluoridation, as quantified by the half-life at physiological pHof the chemical bond that attaches the 18F-atom to the tracer’). Forexample, in some applications it is desirable for the imaging agent tohave a half-life with respect to solvolytic de-18F-fluoridation atphysiological pH that is greater than 10 times the rate of 18F decay. Insome applications it is desirable for the imaging agent to have ahalf-life with respect to solvolytic de-18F-fluoridation atphysiological pH of around 1000 minutes or more. It is noted that therate of solvolytic de-18F-fluoridation is a chemical process thatinvolves bond dissociation, not radioactive decay, and therefore therate of de-18F-fluoridation is equal to that of non-radioactivedefluoridation, where the 18F-fluorine is replaced with a nonradioactive19F-fluorine atom.

The invention described herein is based, in part, on the discovery thatsome organofluoroborates exhibit enhanced resistance to solvolyticde-18F-fluoridation and can be useful as PET imaging agents orprecursors thereof.

An embodiment makes use of a positron emitting compound or salt thereof,wherein the compound may be of the formula I:

wherein:

B is boron;

A may be a linear or branched C₁-C₁₅ alkyl group, a linear or branchedC₁-C₁₅ alkenyl, group, a linear or branched C₁-C₁₅ alkynyl group, or aC₃-C₁₈ non-aromatic cycloalkyl group, wherein each of the C₁-C₁₅ alkylgroup, the linear or branched C₁-C₁₅ alkenyl group, the linear orbranched C₁-C₁₅ alkynyl group, and the C₃-C₁₈ non-aromatic cycloalkylgroup is unsubstituted or substituted and optionally includes at leastone heteroatom interposed between two carbon atoms of the carbon chainof the group, wherein each of the at least one heteroatom isindependently selected from the group consisting of O, S, N and P;

A may be joined to B through a carbon atom;

each Y¹ may independently be selected from the group consisting of R¹,¹⁸F and ¹⁹F;

n=1 or 2;

Y² may be selected from the group consisting of R², ¹⁸F and ¹⁹F;

R¹ may be a non-interfering substituent with regard to fluoridation ofB;

R² may be a non-interfering substituent with regard to fluoridation ofB; and

at least one of (Y¹)_(n) and Y² may be ¹⁸F;

providing that A may be selected such that the pK_(a) of H^(a) of theacid of the formula II:

is less than or equal to about 2.8. When A is substituted at the carbonalpha to the

group with a functional group that has a dissociable proton, thedissociable proton may have a pKa greater than about 9 and contributesto a net positive charge on the functional group. Moieties, A, whenselected so that:

-   -   i) the pK_(a) of H^(a) of the acid of the formula II:

-   -    is less than or equal to 2.8; and    -   ii) when A is substituted at the carbon alpha to the

-   -    group with a functional group that has a dissociable proton,        the dissociable proton has a pKa>9 and contributes to a net        positive charge on the functional group,        permit the resulting fluoroborate to resist defluoridation.        Half-lives with regard to solvolytic de-18F-fluoridation of the        resulting organofluoroborates may be at least about 10 times        longer or more than the rate of decay of 18F. In other        embodiments, half-lives with regard to solvolytic        de-18F-fluoridation of the resulting organofluoroborates may be        at least about 1000 minutes or more; or at least about 5000        minutes or more; or at least about 10000 minutes or more; or at        least about 15000 minutes or more; or at least about 20000        minutes or more; or at least about 25000 minutes or more; or at        least about 50000 minutes or more; or at least about 100000        minutes or more; or at least about 125000 minutes or more; or at        least about 150000 minutes or more. In some applications where        loss of fluorine may be desired (e.g. in comparison of        externally bound ligand that loses fluoride to the surrounding        bone with internalized ligands that keep the fluoride in a        targeted cell) shorter half-lives may be desirable. However, for        whole body imaging, longer half-lives are desirable.

In an embodiment, one or more counterions may be present when thecompound is charged.

In various embodiments, there is provided a method of making a positronemitting compound or salt thereof, the method comprising contacting an¹⁸F source with a compound or salt thereof, wherein the compound may beof the formula I:

wherein:

B is boron;

A may be a linear or branched C₁-C₁₅ alkyl group, a linear or branchedC₁-C₁₅ alkenyl, group, a linear or branched C₁-C₁₅ alkynyl group, or aC₃-C₁₈ non-aromatic cycloalkyl group, wherein each of the C₁-C₁₅ alkylgroup, the linear or branched C₁-C₁₅ alkenyl group, the linear orbranched C₁-C₁₅ alkynyl group, and the C₃-C₁₈ non-aromatic cycloalkylgroup is unsubstituted or substituted and optionally includes at leastone heteroatom interposed between two carbon atoms of the carbon chainof the group, wherein each of the at least one heteroatom isindependently selected from the group consisting of O, S, N and P;

A may be joined to B through a carbon atom;

n=1 or 2;

each Y¹ may independently be selected from the group consisting of R¹and a leaving group that can be displaced by 18F-fluoride;

Y² may be selected from the group consisting of R² and a leaving groupthat can be displaced by fluoride 18F-fluoride;

at least one of (Y¹)_(n) and Y² may be the leaving group when n is 2;

R¹ may be a non-interfering substituent with regard to fluoridation ofB; and

R² may be a non-interfering substituent with regard to fluoridation ofB;

providing that A may be selected such that the pK_(a) of H^(a) of theacid of the formula II:

may be less than or equal to 2.8. When A is substituted at the carbonalpha to the

group with a functional group that has a dissociable proton, thedissociable proton may have a pKa greater than about 9 and contributesto a net positive charge on the functional group.

In various embodiments, there is provided a method of performing PETimaging by administering an imaging-effective amount of a positronemitting compound or salt as defined anywhere herein to a subject orobject to be subjected to PET.

In various embodiments, there is provided a method of selecting a PETimaging agent or precursor thereof having resistance to solvolyticde-18F-fluoridation at physiological pH, the method comprising:

(i) providing one or more compounds or salt thereof wherein the compoundmay be of the formula I:

wherein:

B is boron;

A may be a linear or branched C₁-C₁₅ alkyl group, a linear or branchedC₁-C₁₅ alkenyl, group, a linear or branched C₁-C₁₅ alkynyl group, or aC₃-C₁₈ non-aromatic cycloalkyl group, wherein each of the C₁-C₁₅ alkylgroup, the linear or branched C₁-C₁₅ alkenyl group, the linear orbranched C₁-C₁₅ alkynyl group, and the C₃-C₁₈ non-aromatic cycloalkylgroup is unsubstituted or substituted and optionally includes at leastone heteroatom interposed between two carbon atoms of the carbon chainof the group, wherein each of the at least one heteroatom isindependently selected from the group consisting of O, S, N and P;

A may be joined to B through a carbon atom;

each Y¹ may independently be selected from the group consisting of R¹,¹⁸F and ¹⁹F;

n=1 or 2;

Y² may be selected from the group consisting of R², ¹⁸F and ¹⁹F;

R¹ may be a non-interfering substituent with regard to fluoridation ofB;

R² may be a non-interfering substituent with regard to fluoridation ofB; and

at least one of (Y¹)_(n) and Y² may be ¹⁸F;

providing that A may be selected such that the pK_(a) of H^(a) of theacid of the formula II:

may be less than or equal to about 2.8;

(ii) assessing the half-life of the presence of the fluorine bound to B;and

(iii) selecting a compound or compounds having said half-life of about1000 minutes or more as said imaging agent or precursor thereof. When Ais substituted at the carbon alpha to the

group with a functional group that has a dissociable proton, thedissociable proton may have a pKa greater than about 9 and contributesto a net positive charge on the functional group

In various embodiments, there is provided a conjugate or salt thereofcomprising a peptide conjugated to a positron-emitting compound or saltthereof as described above.

In various embodiments, there is provided a positron emitting compoundor salt thereof as described above, or a peptide conjugated to suchpositron-emitting compound or salt thereof, for use as a PET imagingagent or precursor thereof.

In various embodiments, there is provided a use of a compound or saltthereof as defined in paragraph [0013] above as a precursor in themanufacture of an ¹⁸F containing PET imaging agent.

In various embodiments, the compound may be of the formula (IV):

as defined anywhere herein, provided that when Q¹ is —CR³R⁴R⁵, at leastone of R³, R⁴ and R⁵ is F, Cl, Br, I, CX₃, —N⁺R¹⁵R¹⁶R¹⁷, —P⁺R¹⁸R¹⁹R²⁰,—S⁺R²¹R²² or —NR²³R²⁴.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A, 1C, 1E, 1G, 1I, 1K, 1M, 1O, 1Q, 1S, 1U, 1W, 1Y, 1AA, 1CC, and1EE show ¹⁹F NMR spectral tracers for fluoridated organotrifluoroboratesin 200 mM phosphate buffer pH 7.5, demonstrating the relative amount ofdissociation of ¹⁹F from the compounds at different times.

FIGS. 1B, 1D, IF, 1H, 1J, 1L, 1N, 1P, 1R, 1T, 1V, 1X, 1ZZ, 1BB, 1DD, and1FF show data for solvolytic defluoridation of the fluoridatedorganoborate salts from the ¹⁹F NMR measurement plotted as a function oftime. This plot can be fitted to a pseudo-first-order rate equation thatprovides for the calculation of a rate constant k_(B—F) or alternativelyreferred to as k_(solvolysis).

FIG. 1A shows ¹⁹F NMR spectral traces for a certainalkynyltrifluoroborate (Compound No. 6 of Table 1).

FIG. 1B shows data for solvolytic defluoridation of Compound No. 6 ofTable 1.

FIG. 1C shows ¹⁹F NMR spectral tracers for a quaternaryammoniummethyltrifluoroborate (Compound 9 of Table 1).

FIG. 1D shows data for solvolytic defluoridation of Compound 9 of Table1.

FIG. 1E shows ¹⁹F NMR spectral tracers for butyltrifluoroborate(Compound No. 1 of Table 1).

FIG. 1F shows data for solvolytic defluoridation of Compound No. 1 ofTable 1.

FIG. 1G shows ¹⁹F NMR spectral tracers for vinyltrifluoroborate(Compound No. 2 of Table 1)

FIG. 1H shows data for solvolytic defluoridation of Compound No. 2 ofTable 1.

FIG. 1I shows ¹⁹F NMR spectral tracers for bromomethyltrifluoroborate(Compound No. 4 of Table 1).

FIG. 1J shows data for solvolytic defluoridation of Compound No. 4 ofTable 1).

FIG. 1K shows ¹⁹F NMR spectral tracers for a certainsulfoniumtrifluoroborate (Compound No. 11 of Table 1).

FIG. 1L shows data for solvolytic defluoridation of Compound No. 11 ofTable 1.

FIG. 1M shows ¹⁹F NMR spectral tracers for Compound No. 12 of Table 1.

FIG. 1N shows data for solvolytic defluoridation of Compound No. 12 ofTable 1.

FIG. 1O shows ¹⁹F NMR spectral tracers for phenacyltrifluoroborate(Compound No. 7 of Table 1).

FIG. 1P shows data for solvolytic defluoridation of Compound No. 7 ofTable 1.

FIG. 1Q shows ¹⁹F NMR spectral tracers for benzoytrifluoroborate(Compound No. 8 of Table 1).

FIG. 1R shows data for solvolytic defluoridation of Compound No. 8 ofTable 1.

FIG. 1S shows ¹⁹F NMR spectral tracers forpyridinium-methyltrifluoroborate (Compound No. 13 of Table 1).

FIG. 1T shows data for solvolytic defluoridation of Compound No. 13 ofTable 1.

FIG. 1U shows ¹⁹F NMR spectral tracers for Compound No. 9 of Table 1.

FIG. 1V shows data for solvolytic defluoridation of Compound No. 9 ofTable 1.

FIG. 1W shows ¹⁹F NMR spectral tracers for dichloromethyltrifluoroborate(Compound No. 10 of Table 1).

FIG. 1X shows data for solvolytic defluoridation of Compound No. 10 ofTable 1).

FIG. 1Y shows ¹⁹F NMR spectral tracers for Compound No. 14 of Table 1.

FIG. 1Z shows data for solvolytic defluoridation of Compound No. 14 ofTable 1).

FIG. 1AA shows ¹⁹F NMR spectral tracers for Compound No. 15 of Table 1.

FIG. 1BB shows data for solvolytic defluoridation of Compound No. 15 ofTable 1.

FIG. 1CC shows ¹⁹F NMR spectral tracers for Compound No. 16 of Table 1.

FIG. 1DD shows data for solvolytic defluoridation of Compound No. 16 ofTable 1.

FIG. 1EE shows ¹⁹F NMR spectral tracers for Compound No. 17 of Table 1.

FIG. 1FF shows data for solvolytic defluoridation of Compound No. 17 ofTable 1.

FIG. 2 shows pk_(B—F) values (pk_(B—F)=−log k_(solvolysis)) of a numberof fluoridated organotrifluoroborates i.e. RBF₃ ⁻ compositions plottedas a function of the pKa values for the corresponding carboxylic acidRCOOH. The slope of the graph may be represented as pk(B—F)=−1.40pKa+7.12 (R²=0.994).

FIG. 3 shows TLC chromatograms for Rhodamine-ArBF₃, Rhodamine-PyrBF₃,and Rhodamine-Compound 9 of Table 1. The symbols A, B, C representRhodamine-ArBF₃, Rhodamine-PyrBF₃, and Rhodamine-Compound 9 of Table 1,respectively. The subscript numbers 1, 2, 3 represent different testconditions: Plasma 1, Plasma 2 and PBS buffer (Plasma 1 and Plasma 2were acquired from different mice).

FIG. 4 shows HPLC chromatograms for investigating the serum stability ofRhodamine-Compound 10 of Table 1 at 0 minutes (A), 80 minutes (B), 150minutes (C), 0 minutes (D), 150 minutes (E), and 150 minutes (F).

FIG. 5A shows HPLC traces of radioactivity in the plasma of a mouseinjected with Compound 18 at 0, 80 and 150 min post injection.

FIG. 5B shows PET-CT images of a mouse at 10, 30, and 60 min postinjection with Compound 18.

FIG. 6A shows a histogram indicated the uptake value of different organsfor Compound 19 at 60 min post injection.

FIG. 6B shows a PET/CT image of a mouse injected with Compound 19 at 60min post injection.

FIG. 7 shows PET-CT images of mice injected with Compound 20. T=tumor,K=kidney, B=bladder. The mouse on the left was imaged with Compound 20at 3 Ci/μmol, whereas the mouse on the right was imaged with Compound 20at 0.01 Ci/μmol. The bottom shows a pure CT showing tumors.

DETAILED DESCRIPTION

Any terms not directly defined herein shall be understood to have themeanings commonly associated with them as understood within the art ofthe invention. Certain terms are discussed below, or elsewhere in thespecification, to provide additional guidance to the practitioner indescribing the devices, methods and embodiments of the invention, andhow to make or use them. It will be appreciated that the same thing maybe said in more than one way. Consequently, alternative language andsynonyms may be used for any one or more of the terms discussed herein.No significance is to be placed upon whether or not a term is elaboratedor discussed herein. Some synonyms or substitutable methods, materialsand the like are provided. Recital of one or a few synonyms orequivalents does not exclude use of other synonyms or equivalents,unless it may be explicitly stated. Use of examples in thespecification, including examples of terms, may be for illustrativepurposes only and does not limit the scope and meaning of theembodiments of the invention herein.

“Fluoridation” or “fluorination” are used synonymously herein to refergenerally to a chemical reaction by which fluorine is introduced into acompound.

As used herein, the symbol ‘pKa’ is normally understood to a personskilled in the art and refers to the logarithmic constant, pKa, wherepKa=−log₁₀ Ka. The symbol ‘Ka’ refers to an acid dissociation constant,which is the equilibrium constant for the proton-transfer reactionbetween a weak acid, HA, and water, H₂O. The acid dissociation constant,Ka, for a monoprotic acid, HA, is given by the expressionKa=[A⁻][H₃O⁺]/[HA].

As used herein, the phrase ‘C_(x)-C_(y) alkyl’ group may be used as itis normally understood to a person of skill in the art and often refersto a chemical entity that has a carbon skeleton or main carbon chaincomprising a number from x to y (with all individual integers within therange included, including integers x and y) of carbon atoms. For examplea ‘C₁-C₁₅ alkyl’ group may be a chemical entity that has 1, 2, 3, 4, 5,6, 7, 8, 9, 10, 11, 12, 13, 14 or 15 carbon atom(s) in its carbonskeleton or main chain.

As used herein, the term ‘linear’ may be used as it is normallyunderstood to a person of skill in the art and often refers to achemical entity that comprises a skeleton or main chain that does notsplit off into more that one contiguous chain. Non-limiting examples oflinear alkyls include methyl, ethyl, n-propyl, and n-butyl.

As used herein, the term ‘branched’ may be used as it is normallyunderstood to a person of skill in the art and often refers to achemical entity that comprises a skeleton or main chain that splits offinto more than one contiguous chain. The portions of the skeleton ormain chain that split off in more than one direction may be linear,cyclic or any combination thereof. Non-limiting examples of a branchedalkyl group include tert-butyl and isopropyl.

A linear or branched C₁-C₁₅ alkyl group may include a linear or branchedsaturated C₁-C₁₅ alkyl group, a linear or branched C₂-C₁₅ alkenyl groupand a linear or branched C₂-C₁₅ alkynyl group. As used herein, the term‘saturated’ when referring to a chemical entity may be used as it isnormally understood to a person of skill in the art and often refers toa chemical entity that comprises only single bonds. Non-limitingexamples of saturated C₁-C₁₅ alkyl group may include methyl, ethyl,n-propyl, i-propyl, sec-propyl, n-butyl, i-butyl, sec-butyl, t-butyl,n-pentyl, i-pentyl, sec-pentyl, t-pentyl, n-hexyl, i-hexyl,1,2-dimethylpropyl, 2-ethylpropyl, 1-methyl-2-ethylpropyl,1-ethyl-2-methylpropyl, 1,1,2-trimethylpropyl, 1,1,2-triethylpropyl,1,1-dimethylbutyl, 2,2-dimethylbutyl, 2-ethylbutyl, 1,3-dimethylbutyl,2-methylpentyl, 3-methylpentyl, sec-hexyl, t-hexyl, n-heptyl, i-heptyl,sec-heptyl, t-heptyl, n-octyl, i-octyl, sec-octyl, t-octyl, n-nonyl,i-nonyl, sec-nonyl, t-nonyl, n-decyl, i-decyl, sec-decyl and t-decyl.Non-limiting examples of C₂-C₁₅ alkenyl group may include vinyl, allyl,isopropenyl, 1-propene-2-yl, 1-butene-1-yl, 1-butene-2-yl,1-butene-3-yl, 2-butene-1-yl, 2-butene-2-yl, octenyl and decenyl.Non-limiting examples of C₂-C₁₅ alkynyl group may include ethynyl,propynyl, butynyl, pentynyl, hexynyl, heptynyl, octynyl, nonynyl anddecynyl. The saturated C₁-C₁₅ alkyl group, C₂-C₁₅ alkenyl group orC₂-C₁₅ alkynyl group may be, for example, and without limitation,interrupted by one or more heteroatoms which may independently benitrogen, sulfur, oxygen or phosphorus.

As used herein, the term ‘C_(x)-C_(y) cycloalkyl’ group may be used asit is normally understood to a person of skill in the art and oftenrefers to a compound or a chemical entity in which at least a portion ofthe carbon skeleton or main chain of the chemical entity may be bondedin such a way so as to form a ‘loop’, circle or ring of atoms that arebonded together. The atoms do not have to all be directly bonded to eachother, but rather may be directly bonded to as few as two other atoms inthe ‘loop’. As used herein, C₃-C₁₈ cycloalkyl group may include anon-aromatic C₃-C₁₈ cycloalkyl group and an aromatic C₃-C₁₈ cycloalkylgroup.

A C₃-C₁₈ cycloalkyl group may include, for example, and withoutlimitation, a saturated C₃-C₁₈ cycloalkyl group, a C₃-C₁₈ cycloalkenylgroup, a C₃-C₁₈ cycloalkynyl group, a C₃-C₁₈ aryl group, a C₃-C₁₈non-aromatic heterocyclic group containing one or more heteroatoms whichmay independently be nitrogen, sulfur, phosphorus or oxygen, and aC₃-C₁₈ aromatic heterocyclic group containing one or more heteroatomswhich may independently be nitrogen, sulfur, phosphorus or oxygen.Non-limiting examples of the saturated C₃-C₁₈ cycloalkyl group mayinclude cyclopropanyl, cyclobutanyl, cyclopentanyl, cyclohexanyl,cycloheptanyl, cyclooctanyl, cyclononanyl and cyclodecanyl. Non-limitingexamples of the C₃-C₁₈ cycloalkenyl group may include cyclopropenyl,cyclobutenyl, cyclopentenyl, cyclohexenyl, cycloheptenyl, cyclooctenyl,cyclononanenyl and cyclodecanenyl. Non-limiting examples of the C₃-C₁₈aryl group may include phenyl (Ph), pentalenyl, indenyl, naphthyl, andazulenyl.

Non-limiting examples of the C₃-C₁₈ non-aromatic heterocyclic group mayinclude aziridinyl, azetidinyl, diazetidinyl, pyrrolidinyl, pyrrolinyl,piperidinyl, piperazinyl, imidazolinyl, pyrazolidinyl, imidazolydinyl,phthalimidyl and succinimidyl, oxiranyl, tetrahydropyranyl, oxetanyl,dioxanyl, thietanyl, thiepinyl, morpholinyl, and oxathiolanyl.Non-limiting examples of the C₃-C₁₈ aromatic heterocyclic group mayinclude pyrrolyl, imidazolyl, pyrazolyl, pyridinyl, pyridazinyl,pyrimidinyl, pirazinyl, quinolinyl, isoquinolinyl, acridinyl, indolyl,isoindolyl, indolizinyl, purinyl, carbazolyl, indazolyl, phthalazinyl,naphthyridinyl, quinoxalinyl, quinazolinyl, cinnolinyl, pteridinyl,phenanthridinyl, phenazinyl, phenanthrolinyl, perimidinyl, furyl,dibenzofuryl, xanthenyl, benzofuryl, thiophenyl, thianthrenyl,benzothiophenyl, phosphorinyl, phosphinolinyl, phosphindolyl, thiazolyl,oxazolyl, and isoxazolyl.

As used herein, the term ‘substituted’ may be used as it is normallyunderstood to a person of skill in the art and often refers to achemical entity that has one chemical group replaced with a differentchemical group that contains one or more heteroatoms. Unless otherwisespecified, a substituted alkyl may be an alkyl in which one or morehydrogen atom(s) may be/are replaced with one or more atom(s) that maybe/are not hydrogen(s). For example, chloromethyl may be a non-limitingexample of a substituted alkyl, more particularly an example of asubstituted methyl. Aminoethyl may be another non-limiting example of asubstituted alkyl, more particularly it may be a substituted ethyl.

As used herein, the term ‘unsubstituted’ may be used as it may benormally understood to a person of skill in the art and often refers toa chemical entity that may be a hydrocarbon and/or does not contain aheteroatom. Non-limiting examples of unsubstituted alkyls includemethyl, ethyl, tert-butyl, and pentyl.

“Intercepted”, as used herein with respect to the positioningheteroatoms, pertains to a carbon chain in which a heteroatom isinterposed between two carbon atoms of the carbon chain.

In an embodiment, the compound may be of the formula I:

wherein each of B, A, Y¹, n, Y², R¹, and R² may be as defined anywhereherein.

In further embodiments, A may be selected such that the pKa of H^(a) ofthe acid of the formula II:

may be less than or equal to 5.0, less than or equal to 4.5, less thanor equal to 4.0, less than or equal to 3.5, less than or equal to 3.0,less than or equal to 2.9, less than or equal to 2.8, less than or equalto 2.7, less than or equal to 2.6, less than or equal to 2.5, less thanor equal to 2.4, less than or equal to 2.3, less than or equal to 2.2,less than or equal to 2.1, less than or equal to 2.0, less than or equalto 1.9, less than or equal to 1.8, less than or equal to 1.7, less thanor equal to 1.96, less than or equal to 1.5, less than or equal to 1.4,less than or equal to 1.3, less than or equal to 1.2, less than or equalto 1.1, less than or equal to 1.0, less than or equal to 0.9, less thanor equal to 0.8, less than or equal to 0.6, less than or equal to 0.4,or less than or equal to 0.2. When A is substituted at the carbon alphato the

group with a functional group that has a dissociable proton, thedissociable proton has a pKa>9 and contributes to a net positive chargeon the functional group.

In further embodiments, A may be selected such that the pKa of H^(a) ofthe acid of the formula II:

may be from 0.2 to 0.4, 0.2 to 0.6, 0.2 to 0.8, 0.2 to 1.0, 0.2 to 1.2,0.2 to 1.4, 0.2 to 1.8, 0.2 to 2.0, 0.2 to 2.2, 0.2 to 2.4, 0.2 to 2.6,0.2 to 2.8, 0.2 to 2.9, 0.4 to 2.4, 0.6 to 2.4, 0.8 to 2.4, 1.0 to 2.4,1.2 to 2.4, 1.4 to 2.4, 1.6 to 2.4, 1.8 to 2.4, 2.0 to 2.4, or 2.2 to2.4. When A is substituted at the carbon alpha to the

group with a functional group that has a dissociable proton, thedissociable proton has a pKa>9 and contributes to a net positive chargeon the functional group.

In various embodiments, the positron emitting compound or salt may havea solvolytic de-18F-fluoridation half-life at physiological pH of about1000 minutes or more, about 5000 minutes or more, about 10000 minutes ormore, about 15000 minutes or more, about 20000 minutes or more, about25000 minutes or more, about 50000 minutes or more, about 100000 minutesor more, about 125000 minutes or more, about 150000 minutes or more, orabout 200000 minutes or more. In various embodiments, the positronemitting compound or salt may have a solvolytic de-18F-fluoridationhalf-life at physiological pH from about 1000 minutes to about 200000minutes, from about 5000 minutes to about 200000 minutes, from about10000 minutes to about 200000 minutes, from about 15000 minutes to about200000 minutes, from about 20000 minutes to about 200000 minutes, fromabout 25000 minutes to about 200000 minutes, from about 50000 minutes toabout 200000 minutes, from about 100000 minutes to about 200000 minutes,from about 125000 minutes to about 200000 minutes, or from about 150000minutes to about 200000 minutes.

In various embodiments, the compound may be of the formula (I), whereinA may be substituted with one or more substituents selected from thegroup consisting of F, Cl, Br, I, —N⁺(C₁₋₁₅alkyl)₃, —N⁺(C₂₋₁₅alkenyl)₃,—N⁺(C₂₋₁₅alkynyl)₃, —N⁺H(C₁₋₁₅alkyl)₂, —N⁺H(C₂₋₁₅alkenyl)₂,—N⁺H(C₂₋₁₅alkynyl)₂, P⁺(C₁₋₁₅alkyl)₃, P⁺(C₂₋₁₅alkenyl)₃,P⁺(C₂₋₁₅alkynyl)₃, S⁺(C₁₋₁₅alkyl)₂, S⁺(C₂₋₁₅alkenyl)₂,S⁺(C₂₋₁₅alkynyl)₂, oxo (i.e., ═O), OH, —OC₁₋₁₅alkyl, unsubstituted orsubstituted aromatic C₃-C₁₈ cycloalkyl, unsubstituted or substitutednon-aromatic C₃-C₁₈ heterocyclic group, unsubstituted or substitutedaromatic C₃-C₁₈ heterocyclic group, ═NH, —C₁-C₁₅alkyl, non-aromaticC₃-C₁₈ cycloalkyl, —N(C₁₋₁₅alkyl)₂, —N(C₂₋₁₅alkenyl)₂,—N(C₂₋₁₅alkynyl)₂, —COOH, —NH₂, —SH, a biomolecule, and a linking groupoptionally joined to a biomolecule. In various embodiments, A may besubstituted with one or more substituents selected from the groupconsisting of F, Cl, Br, I, —N⁺(C₁₋₁₅alkyl)₃, —N⁺(C₂₋₁₅alkenyl)₃,—N⁺(C₂₋₁₅alkynyl)₃, —N⁺H(C₁₋₁₅alkyl)₂, —N⁺H(C₂₋₁₅alkenyl)₂,—N⁺H(C₂₋₁₅alkynyl)₂, P⁺(C₁₋₁₅alkyl)₃, P⁺(C₂₋₁₅alkenyl)₃,P⁺(C₂₋₁₅alkynyl)₃, oxo (i.e., ═O), OH, unsubstituted or substitutedaromatic C₃-C₁₈ cycloalkyl, unsubstituted or substituted non-aromaticC₃-C₁₈ heterocyclic group, unsubstituted or substituted aromatic C₃-C₁₈heterocyclic group, ═NH, —C₁-C₁₅alkyl, non-aromatic C₃-C₁₈ cycloalkyl,—N(C₁₋₁₅alkyl)₂, —N(C₂₋₁₅ alkenyl)₂, —N(C₂₋₁₅alkynyl)₂, —COOH, —NH₂,—SH, a biomolecule, and a linking group optionally joined to abiomolecule. In various embodiments, A may be substituted with one ormore substituents selected from the group consisting of F, Cl, Br, I,—N⁺(C₁₋₁₅alkyl)₃, —N⁺(C₂₋₁₅alkenyl)₃, —N⁺(C₂₋₁₅alkynyl)₃,—N⁺H(C₁₋₁₅alkyl)₂, —N⁺H(C₂₋₁₅alkenyl)₂, —N H(C₂₋₁₅alkynyl)₂,P⁺(C₁₋₁₅alkyl)₃, P⁺(C₂₋₁₅alkenyl)₃, P⁺(C₂₋₁₅alkynyl)₃, oxo (i.e., ═O),OH, unsubstituted or substituted aromatic C₃-C₁₈ cycloalkyl,unsubstituted or substituted non-aromatic C₃-C₁₈ heterocyclic group,unsubstituted or substituted aromatic C₃-C₁₈ heterocyclic group,—C₁-C₁₅alkyl, non-aromatic C₃-C₁₈ cycloalkyl, —N(C₁₋₁₅ alkyl)₂,—N(C₂₋₁₅alkenyl)₂, —N(C₂₋₁₅alkynyl)₂, —COOH, —NH₂, —SH, a biomolecule,and a linking group optionally joined to a biomolecule. In variousembodiments, A may be substituted with at least one substituent that maybe a biomolecule or a linking group optionally joined to a biomolecule.

In various embodiments, the compound may be of the formula (IV):

wherein Q¹ may be —CR³R⁴R⁵, —C≡CR⁸,

or —R¹⁰C═CR¹¹R¹²; and each of R³, R⁴, R⁵, R⁸, R⁹, R¹⁰, R¹¹, and R¹² maybe as defined anywhere herein. In various embodiments, Q¹ may be—CR³R⁴R⁵, —C≡CR⁸, or —R¹⁰C═CR¹¹R¹²; and each of R³, R⁴, R⁵, R⁸, R¹⁰,R¹¹, and R¹² may be as defined anywhere herein. In various embodiments,Q¹ may be —CR³R⁴R⁵,

or —R¹⁰C═CR¹¹R¹²; and each of R³, R⁴, R⁵, R⁹, R¹⁰, R¹¹, and R¹² may beas defined anywhere herein. In various embodiments, Q¹ may be —C≡CR⁸,

or —R¹¹C═CR¹¹R¹²; and each of R⁸, R⁹, R¹⁰, R¹¹, and R¹² may be asdefined anywhere herein. In various embodiments, Q¹ may be —CR³R⁴R⁵ or

and each of R³, R⁴, R⁵, and R⁹ may be as defined anywhere herein. Invarious embodiments, Q¹ may be —CR³R⁴R⁵ or —R¹⁰C═CR¹¹R¹²; and each ofR³, R⁴, R⁵, R¹⁰, R¹¹ and R¹² may be as defined anywhere herein. In anembodiment, Q¹ may be —C≡CR⁸ or

and each of R⁸ and R⁹ may be as defined anywhere herein. In anembodiment, Q¹ may be —C≡CR⁸ or —R¹⁰C═CR¹¹R¹²; and each of R⁸, R¹⁰, R¹¹,and R¹² may be as defined anywhere herein. In various embodiments, Q¹may be

or —R¹⁰C═CR¹¹R¹²; and each of R⁹, R¹⁰, R¹¹, and R¹² may be as definedanywhere herein. In an embodiment, Q¹ may be

and R⁹ may be as defined anywhere herein. In an embodiment, Q¹ may be—R¹⁰C═CR¹¹R¹²; and each of R¹⁰, R¹¹, and R¹² may be as defined anywhereherein. In various embodiments, Q¹ may be —CR³R⁴R⁵, —C≡CR⁸, or

and each of R³, R⁴, R⁵, R⁸, and R⁹ may be as defined anywhere herein. Inan embodiment, Q may be —CR³R⁴R⁵ or —C≡CR⁸; and each of R³, R⁴, R⁵, andR⁸ may be as defined anywhere herein. In an embodiment, Q¹ may be—C≡CR⁸; and R⁸ may be as defined anywhere herein. In variousembodiments, Q¹ may be —CR³R⁴R⁵; and each of R³, R⁴, and R⁵ may be asdefined anywhere herein.

In various embodiments, the compound may be of the formula (IV):

wherein Q¹ may be —CR³R⁴R⁵; and each of R³, R⁴, and R⁵ may be as definedanywhere herein. Each of R³, R⁴, and R⁵ may independently be H, D, F,Cl, Br, I, CX₃, —N⁺R¹⁵R¹⁶R¹⁷, —P⁺R¹⁸R¹⁹R²⁰, —S⁺R²¹R²², —NR²³R²⁴, NHR²³,NHR²³, a biomolecule, a linking group optionally joined to abiomolecule, a linear or branched C₁-C₁₅ alkyl group, or a C₃-C₁₈cycloalkyl group, wherein each of the C₁-C₁₅ alkyl group and the C₃-C₁₈cycloalkyl group may be unsubstituted or substituted and may beoptionally intercepted with at least one heteroatom selected from thegroup consisting of O, S, N and P; each of the C₁-C₁₅ alkyl group andthe C₃-C₁₈ cycloalkyl group may be joined to the carbon atom of —CR³R⁴R⁵through a carbon atom; each X may be the same or different and may be F,Cl, Br, or I; each of R¹⁵, R¹⁶, R¹⁷, R¹⁸, R¹⁹, R²⁰, R²¹, R²², R²³ andR²⁴ may be as defined anywhere herein; at least one of R³, R⁴ and R⁵ maybe F, Cl, Br, I, CX₃, —N⁺R¹⁵R¹⁶R¹⁷, —P⁺R¹⁸R¹⁹R²⁰, —S⁺R²¹R²² or —NR²³R²⁴;NHR²³; and at least one of R³, R⁴, R⁵, R¹⁵, R¹⁶, R¹⁷, R¹⁸, R¹⁹, R²⁰,R²¹, R²², R²³, and R²⁴ may be a biomolecule, a linking group optionallyjoined to a biomolecule, or a group that may be substituted with atleast one substituent that may be a biomolecule, or forms a group thatis substituted with at least one substituent that is a biomolecule. Invarious embodiments, at least two of R³, R⁴ and R⁵ may independently beF, Cl, Br, I, or CX₃, or at least one of R³, R⁴ and R⁵ may be—N⁺R¹⁵R¹⁶R¹⁷, —P⁺R¹⁸R¹⁹R²⁰, —S⁺R²¹R²², or —NR²³R²⁴, and at least one ofR³, R⁴, R⁵, R¹⁵, R¹⁶, R¹⁷, R¹, R⁹, R²⁰, R²¹, R²², R²³, and R²⁴ may be abiomolecule, a linking group optionally joined to a biomolecule, or agroup that may be substituted with at least one substituent that may bea biomolecule, or forms a group that is substituted with at least onesubstituent that is a biomolecule. In various embodiments, two of R³, R⁴and R⁵ may independently be F, Cl, Br, I, or CX₃, or one of R³, R⁴ andR⁵ may be —N⁺R¹⁵R¹⁶R¹⁷, —P⁺R¹⁸R¹⁹R²⁰, —S⁺R²¹R²², or —NR²³R²⁴; and atleast one of R³, R⁴, R⁵, R¹⁵, R¹⁶, R¹⁷, R¹⁸, R¹⁹, R²⁰, R²¹, R²², R²³,and R²⁴ may be a biomolecule, a linking group optionally joined to abiomolecule, or a group that may be substituted with at least onesubstituent that may be a biomolecule, or forms a group that issubstituted with at least one substituent that is a biomolecule.

In various embodiments, each of R³, R⁴, and R⁵ may independently be H,D, F, Cl, Br, I, CX₃, —NR¹⁵R¹⁶R¹⁷, —P⁺R¹⁸R¹⁹R²⁰, —S⁺R²¹R²², abiomolecule, a linking group optionally joined to a biomolecule, alinear or branched C₁-C₁₅ alkyl group, or a C₃-C₁₈ cycloalkyl group,wherein each of the C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl groupmay be unsubstituted or substituted and may be optionally interceptedwith at least one heteroatom selected from the group consisting of O, S,N and P; each of the C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl groupmay be joined to the carbon atom of —CR³R⁴R⁵ through a carbon atom; eachX may be the same or different and may be F, Cl, Br, or I; each of R¹⁵,R¹⁶, R¹⁷, R¹⁸, R¹⁹, R⁹, R²¹ and R²² may be as defined anywhere herein;at least one of R³, R⁴ and R⁵ may be F, Cl, Br, I, CX₃, —N⁺R¹⁵R¹⁶R¹⁷,—P⁺R¹⁸R¹⁹R²⁰, or —S⁺R²¹R²²; and at least one of R³, R⁴, R⁵, R¹⁵, R¹⁶,R¹⁷, R¹⁸, R¹⁹, R²⁰, R²¹, and R²² may be a biomolecule, a linking groupoptionally joined to a biomolecule, or a group that may be substitutedwith at least one substituent that may be a biomolecule, or forms agroup that is substituted with at least one substituent that is abiomolecule. In various embodiments, at least two of R³, R⁴ and R⁵ mayindependently be F, Cl, Br, I, or CX₃, or at least one of R³, R⁴ and R⁵may be —N⁺R¹⁵R¹⁶R¹⁷, —P⁺R¹⁸R¹⁹R²⁰, or —S⁺R²¹R²²; and at least one of R³,R⁴, R⁵, R¹⁵, R¹⁶, R¹⁷, R¹⁸, R¹⁹, R²⁰, R²¹, and R²² may be a biomolecule,a linking group optionally joined to a biomolecule, or a group that maybe substituted with at least one substituent that may be a biomolecule,or forms a group that is substituted with at least one substituent thatis a biomolecule. In various embodiments, two of R³, R⁴ and R⁵ mayindependently be F, Cl, Br, I, or CX₃, or one of R³, R⁴ and R⁵ may be—N⁺R¹⁵R¹⁶R¹⁷, —P⁺R¹⁸R¹⁹R²⁰, or —S⁺R²¹R²²; and at least one of R³, R⁴,R⁵, R¹⁵, R¹⁶, R¹⁷, R¹⁸, R¹⁹, R²⁰, R²¹, and R²² may be a biomolecule, alinking group optionally joined to a biomolecule, or a group that may besubstituted with at least one substituent that may be a biomolecule, orforms a group that is substituted with at least one substituent that isa biomolecule.

In various embodiments, each of R³, R⁴, and R⁵ may independently be H,D, F, Cl, Br, I, CX₃, —N⁺R¹⁵R¹⁶R¹⁷, —P⁺R¹⁸R¹⁹R²⁰, —NR²³R²⁴, NHR²³, abiomolecule, a linking group optionally joined to a biomolecule, alinear or branched C₁-C₁₅ alkyl group, or a C₃-C₁₈ cycloalkyl group,wherein each of the C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl groupmay be unsubstituted or substituted and may be optionally interceptedwith at least one heteroatom selected from the group consisting of O, S,N and P; each of the C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl groupmay be joined to the carbon atom of —CR³R⁴R⁵ through a carbon atom; eachX may be the same or different and may be F, Cl, Br, or I; each of R¹⁵,R¹⁶, R¹⁷, R¹⁸, R¹⁹, R²⁰, R²³ and R²⁴ may be as defined anywhere herein;at least one of R³, R⁴ and R⁵ may be F, Cl, Br, I, CX₃, —N⁺R¹⁵R¹⁶R¹⁷,—P⁺R¹⁸R¹⁹R²⁰, or —NR²³R²⁴; and at least one of R³, R⁴, R⁵, R¹⁵, R¹⁶,R¹⁷, R¹⁸, R¹⁹, R²⁰, R²³, and R²⁴ may be a biomolecule, a linking groupoptionally joined to a biomolecule, or a group that may be substitutedwith at least one substituent that may be a biomolecule, or forms agroup that is substituted with at least one substituent that is abiomolecule. In various embodiments, at least two of R³, R⁴ and R⁵ mayindependently be F, Cl, Br, I, or CX₃, or at least one of R³, R⁴ and R⁵may be —N⁺R¹⁵R¹⁶R¹⁷, —P⁺R¹⁸R¹⁹R²⁰, or —NR²³R²⁴; and at least one of R³,R⁴, R⁵, R¹⁵, R¹⁶, R¹⁷, R¹⁸, R¹⁹, R²⁰, R²³, and R²⁴ may be a biomolecule,a linking group optionally joined to a biomolecule, or a group that maybe substituted with at least one substituent that may be a biomolecule,or forms a group that is substituted with at least one substituent thatis a biomolecule. In various embodiments, two of R³, R⁴ and R⁵ mayindependently be F, Cl, Br, I, or CX₃, or one of R³, R⁴ and R⁵ may be—N⁺R¹⁵R¹⁶R¹⁷, —P⁺R¹⁸R¹⁹R²⁰, or NR²³R²⁴; and at least one of R³, R⁴, R⁵,R¹⁵, R¹⁶, R¹⁷, R¹⁸, R¹⁹, R²⁰, R²³, and R²⁴ may be a biomolecule, alinking group optionally joined to a biomolecule, or a group that may besubstituted with at least one substituent that may be a biomolecule, orforms a group that is substituted with at least one substituent that isa biomolecule.

In an embodiment, each of R³, R⁴, and R⁵ may independently be H, D, F,Cl, Br, I, CX₃, —N⁺R¹⁵R¹⁶R¹⁷, —S⁺R²¹R²², —NR²³R²⁴, NHR²³, a biomolecule,a linking group optionally joined to a biomolecule, a linear or branchedC₁-C₁₅ alkyl group, or a C₃-C₁₈ cycloalkyl group, wherein each of theC₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl group may be unsubstitutedor substituted and may be optionally intercepted with at least oneheteroatom selected from the group consisting of O, S, N and P; each ofthe C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl group may be joined tothe carbon atom of —CR³R⁴R⁵ through a carbon atom; each X may be thesame or different and may be F, Cl, Br, or I; each of R¹⁵, R¹⁶, R¹⁷,R²¹, R²², R²³ and R²⁴ may be as defined anywhere herein; at least one ofR³, R⁴ and R⁵ may be F, Cl, Br, I, CX₃, —N⁺R¹⁵R¹⁶R¹⁷, —S⁺R²¹R²² or—NR²³R²⁴; and at least one of R³, R⁴, R⁵, R¹⁵, R¹⁶, R¹⁷, R²¹, R²², R²³,and R²⁴ may be a biomolecule, a linking group optionally joined to abiomolecule, or a group that may be substituted with at least onesubstituent that may be a biomolecule, or forms a group that issubstituted with at least one substituent that is a biomolecule. Invarious embodiments, at least two of R³, R⁴ and R⁵ may independently beF, Cl, Br, I, or CX₃, or at least one of R³, R⁴ and R⁵ may be—N⁺R¹⁵R¹⁶R¹⁷, —S⁺R²¹R²² or —NR²³R²⁴; and at least one of R³, R⁴, R⁵,R¹⁵, R¹⁶, R¹⁷, R²¹, R²², R²³, and R²⁴ may be a biomolecule, a linkinggroup optionally joined to a biomolecule, or a group that may besubstituted with at least one substituent that may be a biomolecule, orforms a group that is substituted with at least one substituent that isa biomolecule. In various embodiments, two of R³, R⁴ and R⁵ mayindependently be F, Cl, Br, I, or CX₃, or one of R³, R⁴ and R⁵ may be—N⁺R¹⁵R¹⁶R¹⁷, —S⁺R²¹R²² or —NR²³R²⁴; and at least one of R³, R⁴, R⁵,R¹⁵, R¹⁶, R¹⁷, R²¹, R²², R²³, and R²⁴ may be a biomolecule, a linkinggroup optionally joined to a biomolecule, or a group that may besubstituted with at least one substituent that may be a biomolecule, orforms a group that is substituted with at least one substituent that isa biomolecule.

In various embodiments, each of R³, R⁴, and R⁵ may independently be H,D, F, Cl, Br, I, CX₃, —P⁺R¹⁸R¹⁹R²⁰, —S⁺R²¹R²², —NR²³R²⁴, a biomolecule,a linking group optionally joined to a biomolecule, a linear or branchedC₁-C₁₅ alkyl group, or a C₃-C₁₈ cycloalkyl group, wherein each of theC₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl group may be unsubstitutedor substituted and may be optionally intercepted with at least oneheteroatom selected from the group consisting of O, S, N and P; each ofthe C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl group may be joined tothe carbon atom of —CR³R⁴R⁵ through a carbon atom; each X may be thesame or different and may be F, Cl, Br, or I; each of R¹⁸, R¹⁹, R²⁰,R²¹, R²², R²³ and R²⁴ may be as defined anywhere herein; at least one ofR³, R⁴ and R⁵ may be F, Cl, Br, I, CX₃, —P⁺R¹⁸R¹⁹R²⁰, —S⁺R²¹R²² or—NR²³R²⁴; and at least one of R³, R⁴, R⁵, R¹⁸, R¹⁹, R²⁰, R²¹, R²², R²³,and R²⁴ may be a biomolecule, a linking group optionally joined to abiomolecule, or a group that may be substituted with at least onesubstituent that may be a biomolecule. In various embodiments, at leasttwo of R³, R⁴ and R⁵ may independently be F, Cl, Br, I, or CX₃, or atleast one of R³, R⁴ and R⁵ may be —P⁺R¹⁸R¹⁹R²⁰, —S⁺R²¹R²² or —NR²³R²⁴;and at least one of R³, R⁴, R⁵, R¹⁸, R¹⁹, R²⁰, R²¹, R²², R²³, and R²⁴may be a biomolecule, a linking group optionally joined to abiomolecule, or a group that may be substituted with at least onesubstituent that may be a biomolecule. In various embodiments, two ofR³, R⁴ and R⁵ may independently be F, Cl, Br, I, or CX₃, or one of R³,R⁴ and R⁵ may be —P⁺R¹⁸R¹⁹R²⁰, —S⁺R²¹R²² or —NR²³R²⁴; and at least oneof R³, R⁴, R⁵, R¹⁸, R¹⁹, R²⁰, R²², R²³, and R²⁴ may be a biomolecule, alinking group optionally joined to a biomolecule, or a group that may besubstituted with at least one substituent that may be a biomolecule.

In an embodiment, each of R³, R⁴, and R⁵ may independently be H, D,—N⁺R¹⁵R¹⁶R¹⁷, —P⁺R¹⁸R¹⁹R²⁰, —S⁺R²¹R²², —NR²³R²⁴, a biomolecule, alinking group optionally joined to a biomolecule, a linear or branchedC₁-C₁₅ alkyl group, or a C₃-C₁₈ cycloalkyl group, wherein each of theC₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl group may be unsubstitutedor substituted and may be optionally intercepted with at least oneheteroatom selected from the group consisting of O, S, N and P; each ofthe C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl group may be joined tothe carbon atom of —CR³R⁴R⁵ through a carbon atom; each of R¹⁵, R¹⁶,R¹⁷, R¹⁸, R¹⁹, R²⁰, R²¹, R²², R²³ and R²⁴ may be as defined anywhereherein; at least one of R³, R⁴ and R⁵ may be —N⁺R¹⁵R¹⁶R¹⁷, —P⁺R¹⁸R¹⁹R²⁰,—S⁺R²¹R²² or —NR²³R²⁴; and at least one of R³, R⁴, R⁵, R¹⁵, R¹⁶, R¹⁷,R¹⁸, R¹⁹, R²⁰, R²¹, R²², R²³, and R²⁴ may be a biomolecule, a linkinggroup optionally joined to a biomolecule, or a group that may besubstituted with at least one substituent that may be a biomolecule, orforms a group that is substituted with at least one substituent that isa biomolecule. In various embodiments, one of R³, R⁴ and R⁵ may be—N⁺R¹⁵R¹⁶R¹⁷, —P⁺R¹⁸R¹⁹R²⁰, —S⁺R²¹R²² or —NR²³R²⁴; and at least one ofR³, R⁴, R⁵, R¹⁵, R¹⁶, R¹⁷, R¹⁸, R¹⁹, R²⁰, R²¹, R²², R²³, and R²⁴ may bea biomolecule, a linking group optionally joined to a biomolecule, or agroup that may be substituted with at least one substituent that may bea biomolecule, or forms a group that is substituted with at least onesubstituent that is a biomolecule.

In an embodiment, each of R³, R⁴, and R⁵ may independently be H, D, F,Cl, Br, I, CX₃, N⁺R¹⁵R¹⁶R¹⁷, —P⁺R¹⁸R¹⁹R²⁰, a biomolecule, a linkinggroup optionally joined to a biomolecule, a linear or branched C₁-C₁₅alkyl group, or a C₃-C₁₈ cycloalkyl group, wherein each of the C₁-C₁₅alkyl group and the C₃-C₁₈ cycloalkyl group may be unsubstituted orsubstituted and may be optionally intercepted with at least oneheteroatom selected from the group consisting of O, S, N and P; each ofthe C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl group may be joined tothe carbon atom of —CR³R⁴R⁵ through a carbon atom; each X may be thesame or different and may be F, Cl, Br, or I; each of R¹⁵, R¹⁶, R¹⁷,R¹⁸, R¹⁹, and R²⁰ may be as defined anywhere herein; at least one of R³,R⁴ and R⁵ may be F, Cl, Br, I, CX₃, —N⁺R¹⁵R¹⁶R¹⁷, or —P⁺R¹⁸R¹⁹R²⁰; andat least one of R³, R⁴, R⁵, R¹⁵, R¹⁶, R¹⁷, R¹⁸, R¹⁹, and R²⁰ may be abiomolecule, a linking group optionally joined to a biomolecule, or agroup that may be substituted with at least one substituent that may bea biomolecule, or forms a group that is substituted with at least onesubstituent that is a biomolecule. In various embodiments, at least twoof R³, R⁴ and R⁵ may independently be F, Cl, Br, I, or CX₃, or at leastone of R³, R⁴ and R⁵ may be —N⁺R¹⁵R¹⁶R¹⁷, or —P⁺R¹⁸R¹⁹R²⁰; and at leastone of R³, R⁴, R⁵, R¹⁵, R¹⁶, R¹⁷, R¹⁸, R¹⁹, and R²⁰ may be abiomolecule, a linking group optionally joined to a biomolecule, or agroup that may be substituted with at least one substituent that may bea biomolecule, or forms a group that is substituted with at least onesubstituent that is a biomolecule. In various embodiments, two of R³, R⁴and R⁵ may independently be F, Cl, Br, I, or CX₃, or one of R³, R⁴ andR⁵ may be —N⁺R¹⁵R¹⁶R¹⁷, or —P⁺R¹⁸R¹⁹R²⁰; and at least one of R³, R⁴, R⁵,R¹⁵, R¹⁶, R¹⁷, R¹⁸, R¹⁹, and R²⁰ may be a biomolecule, a linking groupoptionally joined to a biomolecule, or a group that may be substitutedwith at least one substituent that may be a biomolecule, or forms agroup that is substituted with at least one substituent that is abiomolecule.

In various embodiments, each of R³, R⁴, and R⁵ may independently be H,D, F, Cl, Br, I, CX₃, —NR¹⁵R¹⁶R¹⁷, —S⁺R²¹R²², a biomolecule, a linkinggroup optionally joined to a biomolecule, a linear or branched C₁-C₁₅alkyl group, or a C₃-C₁₈ cycloalkyl group, wherein each of the C₁-C₁₅alkyl group and the C₃-C₁₈ cycloalkyl group may be unsubstituted orsubstituted and may be optionally intercepted with at least oneheteroatom selected from the group consisting of O, S, N and P; each ofthe C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl group may be joined tothe carbon atom of —CR³R⁴R⁵ through a carbon atom; each X may be thesame or different and may be F, Cl, Br, or I; each of R¹⁵, R¹⁶, R¹⁷, R²¹and R²² may be as defined anywhere herein; at least one of R³, R⁴ and R⁵may be F, Cl, Br, I, CX₃, —N⁺R¹⁵R¹⁶R¹⁷, or —S⁺R²¹R²²; and at least oneof R³, R⁴, R⁵, R¹⁵, R¹⁶, R¹⁷, R²¹, and R²² may be a biomolecule, alinking group optionally joined to a biomolecule, or a group that may besubstituted with at least one substituent that may be a biomolecule, orforms a group that is substituted with at least one substituent that isa biomolecule. In various embodiments, at least two of R³, R⁴ and R⁵ mayindependently be F, Cl, Br, I, or CX₃, or at least one of R³, R⁴ and R⁵may be —N⁺R¹⁵R¹⁶R¹⁷, or —S⁺R²¹R²²; and at least one of R³, R⁴, R⁵, R¹⁵,R¹⁶, R¹⁷, R²¹, and R²² may be a biomolecule, a linking group optionallyjoined to a biomolecule, or a group that may be substituted with atleast one substituent that may be a biomolecule, or forms a group thatis substituted with at least one substituent that is a biomolecule. Invarious embodiments, two of R³, R⁴ and R⁵ may independently be F, Cl,Br, I, or CX₃, or one of R³, R⁴ and R⁵ may be —N⁺R¹⁵R¹⁶R¹⁷, or—S⁺R²¹R²²; and at least one of R³, R⁴, R⁵, R¹⁵, R¹⁶, R¹⁷, R²¹, and R²²may be a biomolecule, a linking group optionally joined to abiomolecule, or a group that may be substituted with at least onesubstituent that may be a biomolecule, or forms a group that issubstituted with at least one substituent that is a biomolecule.

In an embodiment, each of R³, R⁴, and R⁵ may independently be H, D, F,Cl, Br, I, CX₃, —N⁺R¹⁵R¹⁶R¹⁷, —NR²³R²⁴, NHR²³, a biomolecule, a linkinggroup optionally joined to, a linear or branched C₁-C₁₅ alkyl group, ora C₃-C₁₈ cycloalkyl group, wherein each of the C₁-C₁₅ alkyl group andthe C₃-C₁₈ cycloalkyl group may be unsubstituted or substituted and maybe optionally intercepted with at least one heteroatom selected from thegroup consisting of O, S, N and P; each of the C₁-C₁₅ alkyl group andthe C₃-C₁₈ cycloalkyl group may be joined to the carbon atom of —CR³R⁴R⁵through a carbon atom; each X may be the same or different and may be F,Cl, Br, or I; each of R¹⁵, R¹⁶, R¹⁷, R²³ and R²⁴ may be as definedanywhere herein; at least one of R³, R⁴ and R⁵ may be F, Cl, Br, I, CX₃,—N⁺R¹⁵R¹⁶R¹⁷, or —NR²³R²⁴; and at least one of R³, R⁴, R⁵, R¹⁵, R¹⁶,R¹⁷, R²³, and R²⁴ may be a biomolecule, a linking group optionallyjoined to a biomolecule, or a group that may be substituted with atleast one substituent that may be a biomolecule, or forms a group thatis substituted with at least one substituent that is a biomolecule. Invarious embodiments, at least two of R³, R⁴ and R⁵ may independently beF, Cl, Br, I, or CX₃, or at least one of R³, R⁴ and R⁵ may be—N⁺R¹⁵R¹⁶R¹⁷, —NR²³R²⁴, or NHR²³; and at least one of R³, R⁴, R⁵, R¹⁵,R¹⁶, R¹⁷, R²³, and R²⁴ may be a biomolecule, a linking group optionallyjoined to a biomolecule, or a group that may be substituted with atleast one substituent that may be a biomolecule, or forms a group thatis substituted with at least one substituent that is a biomolecule. Invarious embodiments, two of R³, R⁴ and R⁵ may independently be F, Cl,Br, I, or CX₃, or one of R³, R⁴ and R⁵ may be —N⁺R¹⁵R¹⁶R¹⁷, or —NR²³R²⁴;and at least one of R³, R⁴, R⁵, R¹⁵, R¹⁶, R¹⁷, R²³, and R²⁴ may be abiomolecule, a linking group optionally joined to a biomolecule, or agroup that may be substituted with at least one substituent that may bea biomolecule, or forms a group that is substituted with at least onesubstituent that is a biomolecule.

In various embodiments, each of R³, R⁴, and R⁵ may independently be H,D, F, Cl, Br, I, CX₃, —P⁺R¹⁸R¹⁹R²⁰, —S⁺R²¹R²², a biomolecule, a linkinggroup optionally joined to a biomolecule, a linear or branched C₁-C₁₅alkyl group, or a C₃-C₁₈ cycloalkyl group, wherein each of the C₁-C₁₅alkyl group and the C₃-C₁₈ cycloalkyl group may be unsubstituted orsubstituted and may be optionally intercepted with at least oneheteroatom selected from the group consisting of O, S, N and P; each ofthe C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl group may be joined tothe carbon atom of —CR³R⁴R⁵ through a carbon atom; each X may be thesame or different and may be F, Cl, Br, or I; each of R¹⁸, R¹⁹, R²⁰, R²¹and R²² may be as defined anywhere herein; at least one of R³, R⁴ and R⁵may be F, Cl, Br, I, CX₃, —P⁺R¹⁸R¹⁹R²⁰, or —S⁺R²¹R²²; and at least oneof R³, R⁴, R⁵, R¹⁸, R¹⁹, R²⁰, R²¹, and R²² may be a biomolecule, alinking group optionally joined to a biomolecule, or a group that may besubstituted with at least one substituent that may be a biomolecule. Invarious embodiments, at least two of R³, R⁴ and R⁵ may independently beF, Cl, Br, I, or CX₃, or at least one of R³, R⁴ and R⁵ may be—P⁺R¹⁸R¹⁹R²⁰, or —S⁺R²¹R²²; and at least one of R³, R⁴, R⁵, R¹⁸, R¹⁹,R²⁰, R²¹, and R²² may be a biomolecule, a linking group optionallyjoined to a biomolecule, or a group that may be substituted with atleast one substituent that may be a biomolecule. In various embodiments,two of R³, R⁴ and R⁵ may independently be F, Cl, Br, I, or CX₃, or oneof R³, R⁴ and R⁵ may be —P⁺R¹⁸R¹⁹R²⁰, or —S⁺R²¹R²²; and at least one ofR³, R⁴, R⁵, R¹⁸, R¹⁹, R²⁰, R²¹, and R²² may be a biomolecule, a linkinggroup optionally joined to a biomolecule, or a group that may besubstituted with at least one substituent that may be a biomolecule.

In various embodiments, each of R³, R⁴, and R⁵ may independently be H,D, F, Cl, Br, I, CX₃, —P⁺R¹⁸R¹⁹R²⁰, —NR²³R²⁴, a biomolecule, a linkinggroup optionally joined to a biomolecule, a linear or branched C₁-C₁₅alkyl group, or a C₃-C₁₈ cycloalkyl group, wherein each of the C₁-C₁₅alkyl group and the C₃-C₁₈ cycloalkyl group may be unsubstituted orsubstituted and may be optionally intercepted with at least oneheteroatom selected from the group consisting of O, S, N and P; each ofthe C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl group may be joined tothe carbon atom of —CR³R⁴R⁵ through a carbon atom; each X may be thesame or different and may be F, Cl, Br, or I; each of R¹⁸, R¹⁹, R²⁰, R²³and R²⁴ may be as defined anywhere herein; at least one of R³, R⁴ and R⁵may be F, Cl, Br, I, CX₃, —P⁺R¹⁸R¹⁹R²⁰, or —NR²³R²⁴ and at least one ofR³, R⁴, R⁵, R¹⁸, R¹⁹, R²⁰, R²³, and R²⁴ may be a biomolecule, a linkinggroup optionally joined to a biomolecule, or a group that may besubstituted with at least one substituent that may be a biomolecule. Invarious embodiments, at least two of R³, R⁴ and R⁵ may independently beF, Cl, Br, I, or CX₃, or at least one of R³, R⁴ and R⁵ may be—P⁺R¹⁸R¹⁹R²⁰, or —NR²³R²⁴ and at least one of R³, R⁴, R⁵, R¹⁸, R¹⁹, R²⁰,R²³, and R²⁴ may be a biomolecule, a linking group optionally joined toa biomolecule, or a group that may be substituted with at least onesubstituent that may be a biomolecule. In various embodiments, two ofR³, R⁴ and R⁵ may independently be F, Cl, Br, I, or CX₃, or one of R³,R⁴ and R⁵ may be —P⁺R¹⁸R¹⁹R²⁰, or —NR²³R²⁴; and at least one of R³, R⁴,R⁵, R¹⁸, R¹⁹, R²⁰, R²³, and R²⁴ may be a biomolecule, a linking groupoptionally joined to a biomolecule, or a group that may be substitutedwith at least one substituent that may be a biomolecule.

In various embodiments, each of R³, R⁴, and R⁵ may independently be H,D, F, Cl, Br, I, CX₃, —S⁺R²¹R²², —NR²³R²⁴, a biomolecule, a linkinggroup optionally joined to a biomolecule, a linear or branched C₁-C₁₅alkyl group, or a C₃-C₁₈ cycloalkyl group, wherein each of the C₁-C₁₅alkyl group and the C₃-C₁₈ cycloalkyl group may be unsubstituted orsubstituted and may be optionally intercepted with at least oneheteroatom selected from the group consisting of O, S, N and P; each ofthe C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl group may be joined tothe carbon atom of —CR³R⁴R⁵ through a carbon atom; each X may be thesame or different and may be F, Cl, Br, or I; each of R²¹, R²², R²³ andR²⁴ may be as defined anywhere herein; at least one of R³, R⁴ and R⁵ maybe F, Cl, Br, I, CX₃, —S⁺R²¹R²² or —NR²³R²⁴; and at least one of R³, R⁴,R⁵, R²¹, R²², R²³, and R²⁴ may be a biomolecule, a linking groupoptionally joined to a biomolecule, or a group that may be substitutedwith at least one substituent that may be a biomolecule. In variousembodiments, at least two of R³, R⁴ and R⁵ may independently be F, Cl,Br, I, or CX₃, or at least one of R³, R⁴ and R⁵ may be —S⁺R²¹R²² or—NR²³R²⁴; and at least one of R³, R⁴, R⁵, R²¹, R²², R²³, and R²⁴ may bea biomolecule, a linking group optionally joined to a biomolecule, or agroup that may be substituted with at least one substituent that may bea biomolecule. In various embodiments, two of R³, R⁴ and R⁵ mayindependently be F, Cl, Br, I, or CX₃, or one of R³, R⁴ and R⁵ may be—S⁺R²¹R²² or —NR²³R²⁴; and at least one of R³, R⁴, R⁵, R²¹, R²², R²³,and R²⁴ may be a biomolecule, a linking group optionally joined to abiomolecule, or a group that may be substituted with at least onesubstituent that may be a biomolecule.

In an embodiment, each of R³, R⁴, and R⁵ may independently be H, D,—N⁺R¹⁵R¹⁶R¹⁷, —P⁺R¹⁸R¹⁹R²⁰, —S⁺R²¹R²², a biomolecule, a linking groupoptionally joined to a biomolecule, a linear or branched C₁-C₁₅ alkylgroup, or a C₃-C₁₈ cycloalkyl group, wherein each of the C₁-C₁₅ alkylgroup and the C₃-C₁₈ cycloalkyl group may be unsubstituted orsubstituted and may be optionally intercepted with at least oneheteroatom selected from the group consisting of O, S, N and P; each ofthe C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl group may be joined tothe carbon atom of —CR³R⁴R⁵ through a carbon atom; each of R¹⁵, R¹⁶,R¹⁷, R¹⁸, R¹⁹, R²⁰, R²¹ and R²² may be as defined anywhere herein; atleast one of R³, R⁴ and R⁵ may be —N⁺R¹⁵R¹⁶R¹⁷, —P⁺R¹⁸R¹⁹R²⁰, or—S⁺R²¹R²²; and at least one of R³, R⁴, R¹⁵, R¹⁶, R¹⁷, R¹⁸, R¹⁹, R²⁰,R²¹, and R²² may be a biomolecule, a linking group optionally joined toa biomolecule, or a group that may be substituted with at least onesubstituent that may be a biomolecule, or forms a group that issubstituted with at least one substituent that is a biomolecule. Invarious embodiments, one of R³, R⁴ and R⁵ may be —N⁺R¹⁵R¹⁶R¹⁷,—P⁺R¹⁸R¹⁹R²⁰, or —S⁺R²¹R²²; and at least one of R³, R⁴, R⁵, R¹⁵, R¹⁶,R¹⁷, R¹⁸, R¹⁹, R²⁰, R²¹, and R²² may be a biomolecule, a linking groupoptionally joined to a biomolecule, or a group that may be substitutedwith at least one substituent that may be a biomolecule, or forms agroup that is substituted with at least one substituent that is abiomolecule.

In an embodiment, each of R³, R⁴, and R⁵ may independently be H, D,—N⁺R¹⁵R¹⁶R¹⁷, —P⁺R¹⁸R¹⁹R²⁰, —NR²³R²⁴, a biomolecule, a linking groupoptionally joined to a biomolecule, a linear or branched C₁-C₁₅ alkylgroup, or a C₃-C₁₈ cycloalkyl group, wherein each of the C₁-C₁₅ alkylgroup and the C₃-C₁₈ cycloalkyl group may be unsubstituted orsubstituted and may be optionally intercepted with at least oneheteroatom selected from the group consisting of O, S, N and P; each ofthe C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl group may be joined tothe carbon atom of —CR³R⁴R⁵ through a carbon atom; each of R¹⁵, R¹⁶,R¹⁷, R¹⁸, R¹⁹, R²⁰, R²³ and R²⁴ may be as defined anywhere herein; atleast one of R³, R⁴ and R⁵ may be —N⁺R¹⁵R¹⁶R¹⁷, —P⁺R¹⁸R¹⁹R²⁰, or—NR²³R²⁴; and at least one of R³, R⁴, R⁵, R¹⁵, R¹⁶, R¹⁷, R¹⁸, R¹⁹, R²⁰,R²³, and R²⁴ may be a biomolecule, a linking group optionally joined toa biomolecule, or a group that may be substituted with at least onesubstituent that may be a biomolecule, or forms a group that issubstituted with at least one substituent that is a biomolecule. Invarious embodiments, one of R³, R⁴ and R⁵ may be —N⁺R¹⁵R¹⁶R¹⁷,—P⁺R¹⁹R²⁰, or —NR²³R²⁴ and at least one of R³, R⁴, R⁵, R¹⁵, R¹⁶, R¹⁷,R¹⁸, R¹⁹, R²⁰, R²³, and R²⁴ may be a biomolecule, a linking groupoptionally joined to a biomolecule, or a group that may be substitutedwith at least one substituent that may be a biomolecule, or forms agroup that is substituted with at least one substituent that is abiomolecule.

In an embodiment, each of R³, R⁴, and R⁵ may independently be H, D,—N⁺R¹⁵R¹⁶R¹⁷, —S⁺R²¹R²², —NR²³R²⁴, a biomolecule, a linking groupoptionally joined to a biomolecule, a linear or branched C₁-C₁₅ alkylgroup, or a C₃-C₁₈ cycloalkyl group, wherein each of the C₁-C₁₅ alkylgroup and the C₃-C₁₈ cycloalkyl group may be unsubstituted orsubstituted and may be optionally intercepted with at least oneheteroatom selected from the group consisting of O, S, N and P; each ofthe C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl group may be joined tothe carbon atom of —CR³R⁴R⁵ through a carbon atom; each of R¹⁵, R¹⁶,R¹⁷, R²¹, R²², R²³ and R²⁴ may be as defined anywhere herein; at leastone of R³, R⁴ and R⁵ may be —N⁺R¹⁵R¹⁶R¹⁷, —S⁺R²¹R²² or —NR²³R²⁴; and atleast one of R³, R⁴, R¹⁵, R¹⁶, R¹⁷, R²¹, R²², R²³, and R²⁴ may be abiomolecule, a linking group optionally joined to a biomolecule, or agroup that may be substituted with at least one substituent that may bea biomolecule, or forms a group that is substituted with at least onesubstituent that is a biomolecule. In various embodiments, one of R³, R⁴and R⁵ may be —N⁺R¹⁵R¹⁶R¹⁷, —S⁺R²¹R²² or —NR²³R²⁴ and at least one ofR³, R⁴, R⁵, R¹⁵, R¹⁶, R¹⁷, R²¹, R²², R²³, and R²⁴ may be a biomolecule,a linking group optionally joined to a biomolecule, or a group that maybe substituted with at least one substituent that may be a biomolecule,or forms a group that is substituted with at least one substituent thatis a biomolecule.

In various embodiments, each of R³, R⁴, and R⁵ may independently be H,D, —P⁺R¹⁸R¹⁹R²⁰, —S⁺R²¹R²², —NR²³R²⁴, a biomolecule, a linking groupoptionally joined to a biomolecule, a linear or branched C₁-C₁₅ alkylgroup, or a C₃-C₁₈ cycloalkyl group, wherein each of the C₁-C₁₅ alkylgroup and the C₃-C₁₈ cycloalkyl group may be unsubstituted orsubstituted and may be optionally intercepted with at least oneheteroatom selected from the group consisting of O, S, N and P; each ofthe C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl group may be joined tothe carbon atom of —CR³R⁴R⁵ through a carbon atom; each of R¹⁸, R¹⁹,R²⁰, R²¹, R²², R²³ and R²⁴ may be as defined anywhere herein; at leastone of R³, R⁴ and R⁵ may be —P⁺R¹⁸R¹⁹R²⁰, —S⁺R²¹R²² or —NR²³R²⁴; and atleast one of R³, R⁴, R⁵, R¹⁸, R¹⁹, R²⁰, R²¹, R²², R²³, and R²⁴ may be abiomolecule, a linking group optionally joined to a biomolecule, or agroup that may be substituted with at least one substituent that may bea biomolecule. In various embodiments, one of R³, R⁴ and R⁵ may be—P⁺R¹⁸R¹⁹R²⁰, —S⁺R²¹R²² or —NR²³R²⁴ and at least one of R³, R⁴, R⁵, R¹⁸,R¹⁹, R²⁰, R²¹, R²², R²³, and R²⁴ may be a biomolecule, a linking groupoptionally joined to a biomolecule, or a group that may be substitutedwith at least one substituent that may be a biomolecule.

In an embodiment, each of R³, R⁴, and R⁵ may independently be H, D, F,Cl, Br, I, CX₃, —P⁺R¹⁸R¹⁹R²⁰, a biomolecule, a linking group optionallyjoined to a biomolecule, a linear or branched C₁-C₁₅ alkyl group, or aC₃-C₁₈ cycloalkyl group, wherein each of the C₁-C₁₅ alkyl group and theC₃-C₁₈ cycloalkyl group may be unsubstituted or substituted and may beoptionally intercepted with at least one heteroatom selected from thegroup consisting of O, S, N and P; each of the C₁-C₁₅ alkyl group andthe C₃-C₁₈ cycloalkyl group may be joined to the carbon atom of —CR³R⁴R⁵through a carbon atom; each X may be the same or different and may be F,Cl, Br, or I; each of R¹⁸, R¹⁹, and R²⁰ may be as defined anywhereherein; at least one of R³, R⁴ and R⁵ may be F, Cl, Br, I, CX₃, or—P⁺R¹⁸R¹⁹R²⁰; and at least one of R³, R⁴, R⁵, R¹⁸, R¹⁹, and R²⁰ may be abiomolecule, a linking group optionally joined to a biomolecule, or agroup that may be substituted with at least one substituent that may bea biomolecule. In various embodiments, at least two of R³, R⁴ and R⁵ mayindependently be F, Cl, Br, I, or CX₃, or at least one of R³, R⁴ and R⁵may be —P⁺R¹⁸R¹⁹R²⁰; and at least one of R³, R⁴, R⁵, R¹⁸, R¹⁹, and R²⁰may be a biomolecule, a linking group optionally joined to abiomolecule, or a group that may be substituted with at least onesubstituent that may be a biomolecule. In various embodiments, two ofR³, R⁴ and R⁵ may independently be F, Cl, Br, I, or CX₃, or one of R³,R⁴ and R⁵ may be —P⁺R¹⁸R¹⁹R²⁰; and at least one of R³, R⁴, R⁵, R¹⁸, R¹⁹,and R²⁰ may be a biomolecule, a linking group optionally joined to abiomolecule, or a group that may be substituted with at least onesubstituent that may be a biomolecule.

In various embodiments, each of R³, R⁴, and R⁵ may independently be H,D, F, Cl, Br, I, CX₃, —S⁺R²¹R²², a biomolecule, a linking groupoptionally joined to a biomolecule, a linear or branched C₁-C₁₅ alkylgroup, or a C₃-C₁₈ cycloalkyl group, wherein each of the C₁-C₁₅ alkylgroup and the C₃-C₁₈ cycloalkyl group may be unsubstituted orsubstituted and may be optionally intercepted with at least oneheteroatom selected from the group consisting of O, S, N and P; each ofthe C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl group may be joined tothe carbon atom of —CR³R⁴R⁵ through a carbon atom; each X may be thesame or different and may be F, Cl, Br, or I; each of R²¹ and R²² may beas defined anywhere herein; at least one of R³, R⁴ and R⁵ may be F, Cl,Br, I, CX₃, or —S⁺R²¹R²²; and at least one of R³, R⁴, R⁵, R²¹, and R²²may be a biomolecule, a linking group optionally joined to abiomolecule, or a group that may be substituted with at least onesubstituent that may be a biomolecule. In various embodiments, at leasttwo of R³, R⁴ and R⁵ may independently be F, Cl, Br, I, or CX₃, or atleast one of R³, R⁴ and R⁵ may be —S⁺R²¹R²²; and at least one of R³, R⁴,R⁵, R²¹, and R²² may be a biomolecule, a linking group optionally joinedto a biomolecule, or a group that may be substituted with at least onesubstituent that may be a biomolecule. In various embodiments, two ofR³, R⁴ and R⁵ may independently be F, Cl, Br, I, or CX₃, or one of R³,R⁴ and R⁵ may be —S⁺R²¹R²²; and at least one of R³, R⁴, R⁵, R²¹, and R²²may be a biomolecule, a linking group optionally joined to abiomolecule, or a group that may be substituted with at least onesubstituent that may be a biomolecule.

In an embodiment, each of R³, R⁴, and R⁵ may independently be H, D, F,Cl, Br, I, CX₃, —NR²³R²⁴, a biomolecule, a linking group optionallyjoined to a biomolecule, a linear or branched C₁-C₁₅ alkyl group, or aC₃-C₁₈ cycloalkyl group, wherein each of the C₁-C₁₅ alkyl group and theC₃-C₁₈ cycloalkyl group may be unsubstituted or substituted and may beoptionally intercepted with at least one heteroatom selected from thegroup consisting of O, S, N and P; each of the C₁-C₁₅ alkyl group andthe C₃-C₁₈ cycloalkyl group may be joined to the carbon atom of —CR³R⁴R⁵through a carbon atom; each X may be the same or different and may be F,Cl, Br, or I; each of R²³ and R²⁴ may be as defined anywhere herein; atleast one of R³, R⁴ and R⁵ may be F, Cl, Br, I, CX₃, or —NR²³R²⁴; and atleast one of R³, R⁴, R⁵, R²³, and R²⁴ may be a biomolecule, a linkinggroup optionally joined to a biomolecule, or a group that may besubstituted with at least one substituent that may be a biomolecule. Invarious embodiments, at least two of R³, R⁴ and R⁵ may independently beF, Cl, Br, I, or CX₃, or at least one of R³, R⁴ and R⁵ may be —NR²³R²⁴;and at least one of R³, R⁴, R⁵, R²³, and R²⁴ may be a biomolecule, alinking group optionally joined to a biomolecule, or a group that may besubstituted with at least one substituent that may be a biomolecule. Invarious embodiments, two of R³, R⁴ and R⁵ may independently be F, Cl,Br, I, or CX₃, or one of R³, R⁴ and R⁵ may be —NR²³R²⁴; and at least oneof R³, R⁴, R⁵, R²³, and R²⁴ may be a biomolecule, a linking groupoptionally joined to a biomolecule, or a group that may be substitutedwith at least one substituent that may be a biomolecule.

In an embodiment, each of R³, R⁴, and R⁵ may independently be H, D,—N⁺R¹⁵R¹⁶R¹⁷, —P⁺R¹⁸R¹⁹R²⁰, a biomolecule, a linking group optionallyjoined to a biomolecule, a linear or branched C₁-C₁₅ alkyl group, or aC₃-C₁₈ cycloalkyl group, wherein each of the C₁-C₁₅ alkyl group and theC₃-C₁₈ cycloalkyl group may be unsubstituted or substituted and may beoptionally intercepted with at least one heteroatom selected from thegroup consisting of O, S, N and P; each of the C₁-C₁₅ alkyl group andthe C₃-C₁₈ cycloalkyl group may be joined to the carbon atom of —CR³R⁴R⁵through a carbon atom; each of R¹⁵, R¹⁶, R¹⁷, R¹⁸, R¹⁹, and R²⁰ may beas defined anywhere herein; at least one of R³, R⁴ and R⁵ may be—N⁺R¹⁵R¹⁶R¹⁷ or —P⁺R¹⁸R¹⁹R²⁰; and at least one of R³, R⁴, R⁵, R¹⁵, R¹⁶,R¹⁷, R¹⁸, R¹⁹, and R²⁰ may be a biomolecule, a linking group optionallyjoined to a biomolecule, or a group that may be substituted with atleast one substituent that may be a biomolecule, or forms a group thatis substituted with at least one substituent that is a biomolecule. Invarious embodiments, one of R³, R⁴ and R⁵ may be —N⁺R¹⁵R¹⁶R¹⁷ or—P⁺R¹⁸R¹⁹R²⁰ and at least one of R³, R⁴, R⁵, R¹⁵, R¹⁶, R¹⁷, R¹⁸, R¹⁹,and R²⁰ may be a biomolecule, a linking group optionally joined to abiomolecule, or a group that may be substituted with at least onesubstituent that may be a biomolecule, or forms a group that issubstituted with at least one substituent that is a biomolecule.

In an embodiment, each of R³, R⁴, and R⁵ may independently be H, D,—N⁺R¹⁵R¹⁶R¹⁷, —S⁺R²¹R²², a biomolecule, a linking group optionallyjoined to a biomolecule, a linear or branched C₁-C₁₅ alkyl group, or aC₃-C₁₈ cycloalkyl group, wherein each of the C₁-C₁₅ alkyl group and theC₃-C₁₈ cycloalkyl group may be unsubstituted or substituted and may beoptionally intercepted with at least one heteroatom selected from thegroup consisting of O, S, N and P; each of the C₁-C₁₅ alkyl group andthe C₃-C₁₈ cycloalkyl group may be joined to the carbon atom of —CR³R⁴R⁵through a carbon atom; each of R¹⁵, R¹⁶, R¹⁷, R²¹ and R²² may be asdefined anywhere herein; at least one of R³, R⁴ and R⁵ may be—N⁺R¹⁵R¹⁶R¹⁷ or —S⁺R²¹R²²; and at least one of R³, R⁴, R⁵, R¹⁵, R¹⁶,R¹⁷, R²¹, and R²² may be a biomolecule, a linking group optionallyjoined to a biomolecule, or a group that may be substituted with atleast one substituent that may be a biomolecule, or forms a group thatis substituted with at least one substituent that is a biomolecule. Invarious embodiments, one of R³, R⁴ and R⁵ may be —N⁺R¹⁵R¹⁶R¹⁷ or—S⁺R²¹R²² and at least one of R³, R⁴, R⁵, R¹⁵, R¹⁶, R¹⁷, R²¹, and R²²may be a biomolecule, a linking group optionally joined to abiomolecule, or a group that may be substituted with at least onesubstituent that may be a biomolecule, or forms a group that issubstituted with at least one substituent that is a biomolecule.

In various embodiments, each of R³, R⁴, and R⁵ may independently be H,D, —N⁺R¹⁵R¹⁶R¹⁷, —NR²³R²⁴, a biomolecule, a linking group optionallyjoined to a biomolecule, a linear or branched C₁-C₁₅ alkyl group, or aC₃-C₁₈ cycloalkyl group, wherein each of the C₁-C₁₅ alkyl group and theC₃-C₁₈ cycloalkyl group may be unsubstituted or substituted and may beoptionally intercepted with at least one heteroatom selected from thegroup consisting of O, S, N and P; each of the C₁-C₁₅ alkyl group andthe C₃-C₁₈ cycloalkyl group may be joined to the carbon atom of —CR³R⁴R⁵through a carbon atom; each of R¹⁵, R¹⁶, R¹⁷, R²³ and R²⁴ may be asdefined anywhere herein; at least one of R³, R⁴ and R⁵ may be—N⁺R¹⁵R¹⁶R¹⁷ or —NR²³R²⁴; and at least one of R³, R⁴, R⁵, R¹⁵, R¹⁶, R¹⁷,R²³, and R²⁴ may be a biomolecule, a linking group optionally joined toa biomolecule, or a group that may be substituted with at least onesubstituent that may be a biomolecule, or forms a group that issubstituted with at least one substituent that is a biomolecule. Invarious embodiments, one of R³, R⁴ and R⁵ may be —N⁺R¹⁵R¹⁶R¹⁷ or—NR²³R²⁴; and at least one of R³, R⁴, R⁵, R¹⁵, R¹⁶, R¹⁷, R²³, and R²⁴may be a biomolecule, a linking group optionally joined to abiomolecule, or a group that may be substituted with at least onesubstituent that may be a biomolecule, or forms a group that issubstituted with at least one substituent that is a biomolecule.

In an embodiment, each of R³, R⁴, and R⁵ may independently be H, D,—P⁺R¹⁸R¹⁹R²⁰, —S⁺R²¹R²², a biomolecule, a linking group optionallyjoined to a biomolecule, a linear or branched C₁-C₁₅ alkyl group, or aC₃-C₁₈ cycloalkyl group, wherein each of the C₁-C₁₅ alkyl group and theC₃-C₁₈ cycloalkyl group may be unsubstituted or substituted and may beoptionally intercepted with at least one heteroatom selected from thegroup consisting of O, S, N and P; each of the C₁-C₁₅ alkyl group andthe C₃-C₁₈ cycloalkyl group may be joined to the carbon atom of —CR³R⁴R⁵through a carbon atom; each of R¹⁸, R¹⁹, R²⁰, R²¹ and R²² may be asdefined anywhere herein; at least one of R³, R⁴ and R⁵ may be—P⁺R¹⁸R¹⁹R²⁰ or —S⁺R²¹R²²; and at least one of R³, R⁴, R⁵, R¹⁸, R¹⁹,R²⁰, R²¹, and R²² may be a biomolecule, a linking group optionallyjoined to a biomolecule, or a group that may be substituted with atleast one substituent that may be a biomolecule. In various embodiments,one of R³, R⁴ and R⁵ may be —P⁺R¹⁸R¹⁹R²⁰ or —S⁺R²¹R²²; and at least oneof R³, R⁴, R⁵, R¹⁸, R¹⁹, R²⁰, R²¹, and R²² may be a biomolecule, alinking group optionally joined to a biomolecule, or a group that may besubstituted with at least one substituent that may be a biomolecule.

In an embodiment, each of R³, R⁴, and R⁵ may independently be H, D,—P⁺R¹⁸R¹⁹R²⁰, —NR²³R²⁴, a biomolecule, a linking group optionally joinedto a biomolecule, a linear or branched C₁-C₁₅ alkyl group, or a C₃-C₁₈cycloalkyl group, wherein each of the C₁-C₁₅ alkyl group and the C₃-C₁₈cycloalkyl group may be unsubstituted or substituted and may beoptionally intercepted with at least one heteroatom selected from thegroup consisting of O, S, N and P; each of the C₁-C₁₅ alkyl group andthe C₃-C₁₈ cycloalkyl group may be joined to the carbon atom of —CR³R⁴R⁵through a carbon atom; each of R¹⁸, R¹⁹, R²⁰, R²³, and R²⁴ may be asdefined anywhere herein; at least one of R³, R⁴ and R⁵ may be—P⁺R¹⁸R¹⁹R²⁰ or —NR²³R²⁴; and at least one of R³, R⁴, R⁵, R¹⁸, R¹⁹, R²⁰,R²³, and R²⁴ may be a biomolecule, a linking group optionally joined toa biomolecule, or a group that may be substituted with at least onesubstituent that may be a biomolecule. In various embodiments, one ofR³, R⁴ and R⁵ may be —P⁺R¹⁸R¹⁹R²⁰ or —NR²³R²⁴; and at least one of R³,R⁴, R⁵, R¹⁸, R¹⁹, R²⁰, R²³, and R²⁴ may be a biomolecule, a linkinggroup optionally joined to a biomolecule, or a group that may besubstituted with at least one substituent that may be a biomolecule.

In an embodiment, each of R³, R⁴, and R⁵ may independently be H, D,—S⁺R²¹R²², —NR²³R²⁴, a biomolecule, a linking group optionally joined toa biomolecule, a linear or branched C₁-C₁₅ alkyl group, or a C₃-C₁₈cycloalkyl group, wherein each of the C₁-C₁₅ alkyl group and the C₃-C₁₈cycloalkyl group may be unsubstituted or substituted and may beoptionally intercepted with at least one heteroatom selected from thegroup consisting of O, S, N and P; each of the C₁-C₁₅ alkyl group andthe C₃-C₁₈ cycloalkyl group may be joined to the carbon atom of —CR³R⁴R⁵through a carbon atom; each of R²¹, R²², R²³ and R²⁴ may be as definedanywhere herein; at least one of R³, R⁴ and R⁵ may be —S⁺R²¹R²² or—NR²³R²⁴; and at least one of R³, R⁴, R⁵, R²¹, R²², R²³, and R²⁴ may bea biomolecule, a linking group optionally joined to a biomolecule, or agroup that may be substituted with at least one substituent that may bea biomolecule. In various embodiments, one of R³, R⁴ and R⁵ may be—S⁺R²¹R²² or —NR²³R²⁴ and at least one of R³, R⁴, R⁵, R²¹, R²², R²³, andR²⁴ may be a biomolecule, a linking group optionally joined to abiomolecule, or a group that may be substituted with at least onesubstituent that may be a biomolecule.

In an embodiment, each of R³, R⁴, and R⁵ may independently be H, D, F,Cl, Br, I, CX₃, —N⁺R¹⁵R¹⁶R¹⁷, a biomolecule, a linking group optionallyjoined to a biomolecule, a linear or branched C₁-C₁₅ alkyl group, or aC₃-C₁₈ cycloalkyl group, wherein each of the C₁-C₁₅ alkyl group and theC₃-C₁₈ cycloalkyl group may be unsubstituted or substituted and may beoptionally intercepted with at least one heteroatom selected from thegroup consisting of O, S, N and P; each of the C₁-C₁₅ alkyl group andthe C₃-C₁₈ cycloalkyl group may be joined to the carbon atom of —CR³R⁴R⁵through a carbon atom; each X may be the same or different and may be F,Cl, Br, or I; each of R¹⁵, R¹⁶ and R¹⁷ may be as defined anywhereherein; at least one of R³, R⁴ and R⁵ may be F, Cl, Br, I, CX₃, or—N⁺R¹⁵R¹⁶R¹⁷; and at least one of R³, R⁴, R⁵, R¹⁵, R¹⁶ and R¹⁷ may be abiomolecule, a linking group optionally joined to a biomolecule, or agroup that may be substituted with at least one substituent that may bea biomolecule, or forms a group that is substituted with at least onesubstituent that is a biomolecule. In various embodiments, at least twoof R³, R⁴ and R⁵ may independently be F, Cl, Br, I, or CX₃, or at leastone of R³, R⁴ and R⁵ may be —N⁺R¹⁵R¹⁶R¹⁷; and at least one of R³, R⁴,R⁵, R¹⁵, R¹⁶ and R¹⁷ may be a biomolecule, a linking group optionallyjoined to a biomolecule, or a group that may be substituted with atleast one substituent that may be a biomolecule, or forms a group thatis substituted with at least one substituent that is a biomolecule. Invarious embodiments, two of R³, R⁴ and R⁵ may independently be F, Cl,Br, I, or CX₃, or one of R³, R⁴ and R⁵ may be —N⁺R¹⁵R¹⁶R¹⁷; and at leastone of R³, R⁴, R⁵, R¹⁵, R¹⁶ and R¹⁷ may be a biomolecule, a linkinggroup optionally joined to a biomolecule, or a group that may besubstituted with at least one substituent that may be a biomolecule, orforms a group that is substituted with at least one substituent that isa biomolecule.

In various embodiments, the compound may be of the formula (IV):

wherein Q¹ may be —CR³R⁴R⁵; and each of R³, R⁴, and R⁵ may independentlybe H, D, F, Cl, Br, I, CX₃, a biomolecule, a linking group optionallyjoined to a biomolecule, a linear or branched C₁-C₁₅ alkyl group, or aC₃-C₁₈ cycloalkyl group, wherein each of the C₁-C₁₅ alkyl group and theC₃-C₁₈ cycloalkyl group may be unsubstituted or substituted and may beoptionally intercepted with at least one heteroatom selected from thegroup consisting of O, S, N and P; each of the C₁-C₁₅ alkyl group andthe C₃-C₁₈ cycloalkyl group may be joined to the carbon atom of —CR³R⁴R⁵through a carbon atom; each X may be the same or different and may be F,Cl, Br, or I; at least one of R³, R⁴ and R⁵ may be F, Cl, Br, I, or CX₃;and at least one of R³, R⁴ and R⁵ may be a biomolecule, a linking groupoptionally joined to a biomolecule, or a group that may be substitutedwith at least one substituent that may be a biomolecule. In variousembodiments, each of R³, R⁴, and R⁵ may independently be F, Cl, Br, I,CX₃, a biomolecule, a linking group optionally joined to a biomolecule,a linear or branched C₁-C₁₅ alkyl group, or a C₃-C₁₈ cycloalkyl group,wherein each of the C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl groupmay be unsubstituted or substituted and may be optionally interceptedwith at least one heteroatom selected from the group consisting of O, S,N and P; each of the C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl groupmay be joined to the carbon atom of —CR³R⁴R⁵ through a carbon atom; eachX may be the same or different and may be F, Cl, Br, or I; two of R³, R⁴and R⁵ may be F, Cl, Br, I, or CX₃; and one of R³, R⁴ and R⁵ may be abiomolecule, a linking group optionally joined to a biomolecule, or agroup that may be substituted with at least one substituent that may bea biomolecule. In various embodiments, two of R³, R⁴, and R⁵ mayindependently be F, Cl, Br, I, or CX₃, and one of R³, R⁴ and R⁵ may be abiomolecule or a linking group optionally joined to a biomolecule. Invarious embodiments, two of R³, R⁴, and R⁵ may independently be F, Cl,Br, I, or CX₃, and one of R³, R⁴ and R⁵ may be a biomolecule. In variousembodiments, two of R³, R⁴, and R⁵ may independently be F, Cl, Br, CX₃,and one of R³, R⁴ and R⁵ may be a biomolecule or a linking groupoptionally joined to a biomolecule. In various embodiments, two of R³,R⁴, and R⁵ may independently be F, Cl, Br, CX₃, and one of R³, R⁴ and R⁵may be a biomolecule. In an embodiment, two of R³, R⁴, and R⁵ mayindependently be F, Br, I, or CX₃, and one of R³, R⁴ and R⁵ may be abiomolecule or a linking group optionally joined to a biomolecule. In anembodiment, two of R³, R⁴, and R⁵ may independently be F, Br, I, or CX₃,and one of R³, R⁴ and R⁵ may be a biomolecule. In various embodiments,two of R³, R⁴, and R⁵ may independently be F, Br, I, or CX₃, and one ofR³, R⁴ and R⁵ may be a biomolecule or a linking group optionally joinedto a biomolecule. In an embodiment, two of R³, R⁴, and R⁵ mayindependently be F, Br, I, or CX₃, and one of R³, R⁴ and R⁵ may be abiomolecule. In an embodiment, two of R³, R⁴, and R⁵ may independentlybe Cl, Br, I, or CX₃, and one of R³, R⁴ and R⁵ may be a biomolecule or alinking group optionally joined to a biomolecule. In variousembodiments, two of R³, R⁴, and R⁵ may independently be Cl, Br, I, orCX₃, and one of R³, R⁴ and R⁵ may be a biomolecule. In an embodiment,two of R³, R⁴, and R⁵ may independently be F, Cl, or I, and one of R³,R⁴ and R⁵ may be a biomolecule or a linking group optionally joined to abiomolecule. In an embodiment, two of R³, R⁴, and R⁵ may independentlybe F, Cl, or I, and one of R³, R⁴ and R⁵ may be a biomolecule. In anembodiment, two of R³, R⁴, and R⁵ may independently be F, Cl, or CX₃,and one of R³, R⁴ and R⁵ may be a biomolecule or a linking groupoptionally joined to a biomolecule. In an embodiment, two of R³, R⁴, andR⁵ may independently be F, Cl, or CX₃, and one of R³, R⁴ and R⁵ may be abiomolecule. In various embodiments, two of R³, R⁴, and R⁵ mayindependently be F, Br, or I, and one of R³, R⁴ and R⁵ may be abiomolecule or a linking group optionally joined to a biomolecule. In anembodiment, two of R³, R⁴, and R⁵ may independently be F, Br, or I, andone of R³, R⁴ and R⁵ may be a biomolecule. In various embodiments, twoof R³, R⁴, and R⁵ may independently be F, Br, or CX₃, and one of R³, R⁴and R⁵ may be a biomolecule or a linking group optionally joined to abiomolecule. In an embodiment, two of R³, R⁴, and R⁵ may independentlybe F, Br, or CX₃, and one of R³, R⁴ and R⁵ may be a biomolecule. Invarious embodiments, two of R³, R⁴, and R⁵ may independently be F, I, orCX₃, and one of R³, R⁴ and R⁵ may be a biomolecule or a linking groupoptionally joined to a biomolecule. In an embodiment, two of R³, R⁴, andR⁵ may independently be F, I, or CX₃, and one of R³, R⁴ and R⁵ may be abiomolecule. In various embodiments, two of R³, R⁴, and R⁵ mayindependently be Cl, Br, or I, and one of R³, R⁴ and R⁵ may be abiomolecule or a linking group optionally joined to a biomolecule. In anembodiment, two of R³, R⁴, and R⁵ may independently be Cl, Br, or I, andone of R³, R⁴ and R⁵ may be a biomolecule. In an embodiment, two of R³,R⁴, and R⁵ may independently be Cl, Br, or CX₃, and one of R³, R⁴ and R⁵may be a biomolecule or a linking group optionally joined to abiomolecule. In an embodiment, two of R³, R⁴, and R⁵ may independentlybe Cl, Br, or CX₃, and one of R³, R⁴ and R⁵ may be a biomolecule. In anembodiment, two of R³, R⁴, and R⁵ may independently be Cl, I, or CX₃,and one of R³, R⁴ and R⁵ may be a biomolecule or a linking groupoptionally joined to a biomolecule. In an embodiment, two of R³, R⁴, andR⁵ may independently be Cl, I, or CX₃, and one of R³, R⁴ and R⁵ may be abiomolecule. In an embodiment, two of R³, R⁴, and R⁵ may independentlybe Br, I, or CX₃, and one of R³, R⁴ and R⁵ may be a biomolecule or alinking group optionally joined to a biomolecule. In an embodiment, twoof R³, R⁴, and R⁵ may independently be Br, I, or CX₃, and one of R³, R⁴and R⁵ may be a biomolecule. In an embodiment, two of R³, R⁴, and R⁵ mayindependently be F or Br, and one of R³, R⁴ and R⁵ may be a biomoleculeor a linking group optionally joined to a biomolecule. In an embodiment,two of R³, R⁴, and R⁵ may independently be F or Br, and one of R³, R⁴and R⁵ may be a biomolecule. In an embodiment, two of R³, R⁴, and R⁵ mayindependently be F or I, and one of R³, R⁴ and R⁵ may be a biomoleculeor a linking group optionally joined to a biomolecule. In an embodiment,two of R³, R⁴, and R⁵ may independently be F or I, and one of R³, R⁴ andR⁵ may be a biomolecule. In an embodiment, two of R³, R⁴, and R⁵ mayindependently be F or CX₃, and one of R³, R⁴ and R⁵ may be a biomoleculeor a linking group optionally joined to a biomolecule. In an embodiment,two of R³, R⁴, and R⁵ may independently be F or CX₃, and one of R³, R⁴and R⁵ may be a biomolecule. In an embodiment, two of R³, R⁴, and R⁵ mayindependently be Cl or Br, and one of R³, R⁴ and R⁵ may be a biomoleculeor a linking group optionally joined to a biomolecule. In an embodiment,two of R³, R⁴, and R⁵ may independently be Cl or Br, and one of R³, R⁴and R⁵ may be a biomolecule. In an embodiment, two of R³, R⁴, and R⁵ mayindependently be Cl or I, and one of R³, R⁴ and R⁵ may be a biomoleculeor a linking group optionally joined to a biomolecule. In an embodiment,two of R³, R⁴, and R⁵ may independently be Cl or I, and one of R³, R⁴and R⁵ may be a biomolecule. In an embodiment, two of R³, R⁴, and R⁵ mayindependently be Cl or CX₃, and one of R³, R⁴ and R⁵ may be abiomolecule or a linking group optionally joined to a biomolecule. In anembodiment, two of R³, R⁴, and R⁵ may independently be Cl or CX₃, andone of R³, R⁴ and R⁵ may be a biomolecule. In an embodiment, two of R³,R⁴, and R⁵ may independently be Br or I, and one of R³, R⁴ and R⁵ may bea biomolecule or a linking group optionally joined to a biomolecule. Inan embodiment, two of R³, R⁴, and R⁵ may independently be Br or I, andone of R³, R⁴ and R⁵ may be a biomolecule. In an embodiment, two of R³,R⁴, and R⁵ may independently be Br or CX₃, and one of R³, R⁴ and R⁵ maybe a biomolecule or a linking group optionally joined to a biomolecule.In an embodiment, two of R³, R⁴, and R⁵ may independently be Br or CX₃,and one of R³, R⁴ and R⁵ may be a biomolecule. In an embodiment, two ofR³, R⁴, and R⁵ may independently be I or CX₃, and one of R³, R⁴ and R⁵may be a biomolecule or a linking group optionally joined to abiomolecule. In an embodiment, two of R³, R⁴, and R⁵ may independentlybe I or CX₃, and one of R³, R⁴ and R⁵ may be a biomolecule. In anembodiment, two of R³, R⁴, and R⁵ may be CX₃, and one of R³, R⁴ and R⁵may be a biomolecule or a linking group optionally joined to abiomolecule. In an embodiment, two of R³, R⁴, and R⁵ may be CX₃, and oneof R³, R⁴ and R⁵ may be a biomolecule. In an embodiment, two of R³, R⁴,and R⁵ may be Cl, and one of R³, R⁴ and R⁵ may be a biomolecule or alinking group optionally joined to a biomolecule. In an embodiment, twoof R³, R⁴, and R⁵ may be Cl, and one of R³, R⁴ and R⁵ may be abiomolecule. In an embodiment, two of R³, R⁴, and R⁵ may be Br, and oneof R³, R⁴ and R⁵ may be a biomolecule or a linking group optionallyjoined to a biomolecule. In an embodiment, two of R³, R⁴, and R⁵ may beBr, and one of R³, R⁴ and R⁵ may be a biomolecule. In an embodiment, twoof R³, R⁴, and R⁵ may be I, and one of R³, R⁴ and R⁵ may be abiomolecule or a linking group optionally joined to a biomolecule. In anembodiment, two of R³, R⁴, and R⁵ may be I, and one of R³, R⁴ and R⁵ maybe a biomolecule. In various embodiments, two of R³, R⁴, and R⁵ mayindependently be F, Cl, Br, or I, and one of R³, R⁴ and R⁵ may be abiomolecule or a linking group optionally joined to a biomolecule. Invarious embodiments, two of R³, R⁴, and R⁵ may independently be F, Cl,Br, or I, and one of R³, R⁴ and R⁵ may be a biomolecule. In anembodiment, two of R³, R⁴, and R⁵ may independently be F, Cl, or Br, andone of R³, R⁴ and R⁵ may be a biomolecule or a linking group optionallyjoined to a biomolecule. In an embodiment, two of R³, R⁴, and R⁵ mayindependently be F, Cl, or Br, and one of R³, R⁴ and R⁵ may be abiomolecule. In an embodiment, two of R³, R⁴, and R⁵ may independentlybe F or Cl, and one of R³, R⁴ and R⁵ may be a biomolecule or a linkinggroup optionally joined to a biomolecule. In an embodiment, two of R³,R⁴, and R⁵ may independently be F or Cl, and one of R³, R⁴ and R⁵ may bea biomolecule. In an embodiment, two of R³, R⁴, and R⁵ may be F, and oneof R³, R⁴ and R⁵ may be a biomolecule or a linking group optionallyjoined to a biomolecule. In an embodiment, two of R³, R⁴, and R⁵ may beF, and one of R³, R⁴ and R⁵ may be a biomolecule. In an embodiment, eachX may be the same or different and may be F, Cl, Br, or I. In variousembodiments, each X may be the same or different and may be F, Cl, or I.In various embodiments, each X may be the same or different and may beF, Br, or I. In an embodiment, each X may be the same or different andmay be Cl, Br, or I. In an embodiment, each X may be the same ordifferent and may be F or Br. In an embodiment, each X may be the sameor different and may be F or I. In an embodiment, each X may be the sameor different and may be Cl or Br. In an embodiment, each X may be thesame or different and may be Cl or I. In an embodiment, each X may bethe same or different and may be Br or I. In an embodiment, each X maybe Cl. In an embodiment, each X may be Br. In an embodiment, each X maybe I. In various embodiments, each X may be the same or different andmay be F, Cl, Br. In an embodiment, each X may be the same or differentand may be F or Cl. In an embodiment, each X may be F.

In various embodiments, the compound may be of the formula (IV):

wherein Q¹ may be —CR³R⁴R⁵; and each of R³, R⁴, and R⁵ may independentlybe H, D, —N⁺R¹⁵R¹⁶R¹⁷, a biomolecule, a linking group optionally joinedto a biomolecule, a linear or branched C₁-C₁₅ alkyl group, or a C₃-C₁₈cycloalkyl group, wherein each of the C₁-C₁₅ alkyl group and the C₃-C₁₈cycloalkyl group may be unsubstituted or substituted and may beoptionally intercepted with at least one heteroatom selected from thegroup consisting of O, S, N and P; each of the C₁-C₁₅ alkyl group andthe C₃-C₁₈ cycloalkyl group may be joined to the carbon atom of —CR³R⁴R⁵through a carbon atom; each of R¹⁵, R¹⁶ and R¹⁷ may independently be H,D, a biomolecule, a linking group optionally joined to a biomolecule, alinear or branched C₁-C₁₅ alkyl group, or a C₃-C₁₈ cycloalkyl group,wherein each of the C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl groupmay be unsubstituted or substituted and may be optionally interceptedwith at least one heteroatom selected from the group consisting of O, S,N and P, each of the C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl groupmay be joined to the nitrogen atom of —N⁺R¹⁵R¹⁶R¹⁷ through a carbonatom, or R¹⁵ may be absent and R¹⁶ and R¹⁷ may be joined so that—N⁺R¹⁵R¹⁶R¹⁷ forms a positively charged nitrogen containing heterocyclicgroup which may be substituted or unsubstituted; at least one of R³, R⁴and R⁵ may be —N⁺R¹⁵R¹⁶R¹⁷; and at least one of R³, R⁴, R⁵, R¹⁵, R¹⁶,and R¹⁷ may be a biomolecule, a linking group optionally joined to abiomolecule, or a group that may be substituted with at least onesubstituent that may be a biomolecule, or forms a group that issubstituted with at least one substituent that is a biomolecule. Invarious embodiments, R³ may be —N⁺R¹⁵R¹⁶R¹⁷; each of each of R⁴ and R⁵may independently be H, D, a biomolecule, a linking group optionallyjoined to a biomolecule, a linear or branched C₁-C₁₅ alkyl group, or aC₃-C₁₈ cycloalkyl group, wherein each of the C₁-C₁₅ alkyl group and theC₃-C₁₈ cycloalkyl group may be unsubstituted or substituted and may beoptionally intercepted with at least one heteroatom selected from thegroup consisting of O, S, N and P; each of the C₁-C₁₅ alkyl group andthe C₃-C₁₈ cycloalkyl group may be joined to the carbon atom of —CR³R⁴R⁵through a carbon atom; each of R¹⁵, R¹⁶ and R¹⁷ may independently be H,D, a biomolecule, a linking group optionally joined to a biomolecule, alinear or branched C₁-C₁₅ alkyl group, or a C₃-C₁₈ cycloalkyl group,wherein each of the C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl groupmay be unsubstituted or substituted and may be optionally interceptedwith at least one heteroatom selected from the group consisting of O, S,N and P, each of the C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl groupmay be joined to the nitrogen atom of —N⁺R¹⁵R¹⁶R¹⁷ through a carbonatom, or R¹⁵ may be absent and R¹⁶ and R¹⁷ may be joined so that—N⁺R¹⁵R¹⁶R¹⁷ forms a positively charged nitrogen containing heterocyclicgroup which may be substituted or unsubstituted; and at least one of R⁴,R⁵, R¹⁵, R¹⁶ and R¹⁷ may be a biomolecule, a linking group optionallyjoined to a biomolecule, or a group that may be substituted with atleast one substituent that may be a biomolecule, or forms a group thatis substituted with at least one substituent that is a biomolecule. Inan embodiment, each of R¹⁵, R¹⁶ and R¹⁷ may independently be H, D, abiomolecule, a linking group optionally joined to a biomolecule, alinear or branched C₁-C₁₅ alkyl group, or a C₃-C₁₈ cycloalkyl group,wherein each of the C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl groupmay be unsubstituted or substituted and may be optionally interceptedwith at least one heteroatom selected from the group consisting of O, S,N and P, and each of the C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkylgroup may be joined to the nitrogen atom of —N⁺R¹⁵R¹⁶R¹⁷ through acarbon atom. In various embodiments, R¹⁵ may be absent and R¹⁶ and R¹⁷may be joined so that —N⁺R¹⁵R¹⁶R¹⁷ forms a positively charged nitrogencontaining heterocyclic group which may be substituted or unsubstituted.In various embodiments, R¹⁵ may be absent and R¹⁶ and R¹⁷ may be joinedso that —NR¹⁵R¹⁶R¹⁷ forms a positively charged 4 to 6-membered nitrogencontaining heterocyclic group which may be substituted or unsubstituted.In an embodiment, the positively charged 4 to 6-membered nitrogencontaining heterocyclic group may be a pyridinium group, an imidazoliumgroup, a pyrazinium group, a pyrimidinium group or a pyridazinium group,each of which may be substituted or unsubstituted. In variousembodiments, the positively charged nitrogen containing heterocyclicgroup may be unsubstituted. In various embodiments, the positivelycharged nitrogen containing heterocyclic group which may be substitutedwith one or more substituents that are selected from the groupconsisting of a C₁-C₁₅ alkyl group, a biomolecule, a linking groupoptionally joined to a biomolecule. In various embodiments, the C₁-C₁₅alkyl group may be a C₁-C₆ alkyl group. In various embodiments, theC₃-C₁₈ cycloalkyl group may be a C₄-C₈ cycloalkyl group.

In various embodiments, the compound may be of the formula (IV):

wherein Q¹ may be —CR³R⁴R⁵; and each of R³, R⁴, and R⁵ may independentlybe H, D, —P⁺R¹⁸R¹⁹R²⁰, a biomolecule, a linking group optionally joinedto a biomolecule, a linear or branched C₁-C₁₅ alkyl group, or a C₃-C₁₈cycloalkyl group, wherein each of the C₁-C₁₅ alkyl group and the C₃-C₁₈cycloalkyl group may be unsubstituted or substituted and may beoptionally intercepted with at least one heteroatom selected from thegroup consisting of O, S, N and P; each of the C₁-C₁₅ alkyl group andthe C₃-C₁₈ cycloalkyl group may be joined to the carbon atom of —CR³R⁴R⁵through a carbon atom; each of R¹⁸, R¹⁹, and R²⁰ may independently be H,D, a biomolecule, a linking group optionally joined to a biomolecule, alinear or branched C₁-C₁₅ alkyl group, or a C₃-C₁₈ cycloalkyl group,wherein each of the C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl groupmay be unsubstituted or substituted and may be optionally interceptedwith at least one heteroatom selected from the group consisting of O, S,N and P; each of the C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl groupmay be joined to the phosphorus atom of —P⁺R¹⁸R¹⁹R²⁰ through a carbonatom; at least one of R³, R⁴ and R⁵ may be —P⁺R¹⁸R¹⁹R²⁰; and at leastone of R³, R⁴, R⁵, R¹⁸, R¹⁹, and R²⁰ may be a biomolecule, a linkinggroup optionally joined to a biomolecule, or a group that may besubstituted with at least one substituent that may be a biomolecule. Invarious embodiments, R³ may be —P⁺R¹⁸R¹⁹R²⁰; each of R⁴ and R⁵ mayindependently be H, D, a biomolecule, a linking group optionally joinedto a biomolecule, a linear or branched C₁-C₁₅ alkyl group, or a C₃-C₁₈cycloalkyl group, wherein each of the C₁-C₁₅ alkyl group and the C₃-C₁₈cycloalkyl group may be unsubstituted or substituted and may beoptionally intercepted with at least one heteroatom selected from thegroup consisting of O, S, N and P; each of the C₁-C₁₅ alkyl group andthe C₃-C₁₈ cycloalkyl group may be joined to the carbon atom of —CR³R⁴R⁵through a carbon atom; each of R¹⁸, R¹⁹ and R²⁰ may independently be H,D, a biomolecule, a linking group optionally joined to a biomolecule, alinear or branched C₁-C₁₅ alkyl group, or a C₃-C₁₈ cycloalkyl group,wherein each of the C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl groupmay be unsubstituted or substituted and may be optionally interceptedwith at least one heteroatom selected from the group consisting of O, S,N and P; each of the C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl groupmay be joined to the phosphorus atom of —P⁺R¹⁸R¹⁹R²⁰ through a carbonatom; and at least one of R⁴, R⁵, R¹⁸, R¹⁹, and R²⁰ may be abiomolecule, a linking group optionally joined to a biomolecule, or agroup that may be substituted with at least one substituent that may bea biomolecule. In various embodiments, the C₁-C₁₅ alkyl group may be aC₁-C₆ alkyl group. In various embodiments, the C₃-C₁₈ cycloalkyl groupmay be a C₄-C₈ cycloalkyl group.

In various embodiments, the compound may be of the formula (IV):

wherein Q¹ may be —CR³R⁴R⁵; and each of R³, R⁴, and R⁵ may independentlybe H, D, —S⁺R²¹R²², a biomolecule, a linking group optionally joined toa biomolecule, a linear or branched C₁-C₁₅ alkyl group, or a C₃-C₁₈cycloalkyl group, wherein each of the C₁-C₁₅ alkyl group and the C₃-C₁₈cycloalkyl group may be unsubstituted or substituted and may beoptionally intercepted with at least one heteroatom selected from thegroup consisting of O, S, N and P; each of the C₁-C₁₅ alkyl group andthe C₃-C₁₈ cycloalkyl group may be joined to the carbon atom of —CR³R⁴R⁵through a carbon atom; each of R²¹ and R²² may independently be H, D, abiomolecule, a linking group optionally joined to a biomolecule, alinear or branched C₁-C₁₅ alkyl group, or a C₃-C₁₈ cycloalkyl group,wherein each of the C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl groupmay be unsubstituted or substituted and may be optionally interceptedwith at least one heteroatom selected from the group consisting of O, S,N and P; each of the C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl groupmay be joined to the sulfur atom of —S⁺R²¹R²² through a carbon atom; atleast one of R³, R⁴ and R⁵ may be —S⁺R²¹R²²; and at least one of R³, R⁴,R⁵, R²¹, and R²² may be a biomolecule, a linking group optionally joinedto a biomolecule, or a group that may be substituted with at least onesubstituent that may be a biomolecule. In various embodiments, R³ may be—S⁺R²¹R²²; each of R⁴ and R⁵ may independently be H, D, a biomolecule, alinking group optionally joined to a biomolecule, a linear or branchedC₁-C₁₅ alkyl group, or a C₃-C₁₈ cycloalkyl group, wherein each of theC₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl group may be unsubstitutedor substituted and may be optionally intercepted with at least oneheteroatom selected from the group consisting of O, S, N and P; each ofthe C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl group may be joined tothe carbon atom of —CR³R⁴R⁵ through a carbon atom; each of R²¹ and R²²may independently be H, D, a biomolecule, a linking group optionallyjoined to a biomolecule, a linear or branched C₁-C₁₅ alkyl group, or aC₃-C₁₈ cycloalkyl group, wherein each of the C₁-C₁₅ alkyl group and theC₃-C₁₈ cycloalkyl group may be unsubstituted or substituted and may beoptionally intercepted with at least one heteroatom selected from thegroup consisting of O, S, N and P; each of the C₁-C₁₅ alkyl group andthe C₃-C₁₈ cycloalkyl group may be joined to the sulfur atom of—S⁺R²¹R²² through a carbon atom; and at least one of R⁴, R⁵, R²¹, andR²² may be a biomolecule, a linking group optionally joined to abiomolecule, or a group that may be substituted with at least onesubstituent that may be a biomolecule. In various embodiments, theC₁-C₁₅ alkyl group may be a C₁-C₆ alkyl group. In various embodiments,the C₃-C₁₈ cycloalkyl group may be a C₄-C₈ cycloalkyl group.

In various embodiments, the compound may be of the formula (IV):

wherein Q¹ may be —CR³R⁴R⁵; and each of R³, R⁴, and R⁵ may independentlybe H, D, —NR²³R²⁴, a biomolecule, a linking group optionally joined to abiomolecule, a linear or branched C₁-C₁₅ alkyl group, or a C₃-C₁₈cycloalkyl group, wherein each of the C₁-C₁₅ alkyl group and the C₃-C₁₈cycloalkyl group may be unsubstituted or substituted and may beoptionally intercepted with at least one heteroatom selected from thegroup consisting of O, S, N and P; each of the C₁-C₁₅ alkyl group andthe C₃-C₁₈ cycloalkyl group may be joined to the carbon atom of —CR³R⁴R⁵through a carbon atom; each of R²³ and R²⁴ may independently be H, D, abiomolecule, a linking group optionally joined to a biomolecule, alinear or branched C₁-C₁₅ alkyl group, or a C₃-C₁₈ cycloalkyl group,wherein each of the C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl groupmay be unsubstituted or substituted and may be optionally interceptedwith at least one heteroatom selected from the group consisting of O, S,N and P; each of the C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl groupmay be joined to the nitrogen atom of —NR²³R²⁴ through a carbon atom; atleast one of R³, R⁴ and R⁵ may be —NR²³R²⁴; and at least one of R³, R⁴,R⁵, R²³, and R²⁴ may be a biomolecule, a linking group optionally joinedto a biomolecule, or a group that may be substituted with at least onesubstituent that may be a biomolecule. In various embodiments, R³ may be—NR²³R²⁴; each of R⁴ and R⁵ may independently be H, D, a biomolecule, alinking group optionally joined to a biomolecule, a linear or branchedC₁-C₁₅ alkyl group, or a C₃-C₁₈ cycloalkyl group, wherein each of theC₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl group may be unsubstitutedor substituted and may be optionally intercepted with at least oneheteroatom selected from the group consisting of O, S, N and P; each ofthe C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl group may be joined tothe carbon atom of —CR³R⁴R⁵ through a carbon atom; each of R²³ and R²⁴may independently be H, D, a biomolecule, a linking group optionallyjoined to a biomolecule, a linear or branched C₁-C₁₅ alkyl group, or aC₃-C₁₈ cycloalkyl group, wherein each of the C₁-C₁₅ alkyl group and theC₃-C₁₈ cycloalkyl group may be unsubstituted or substituted and may beoptionally intercepted with at least one heteroatom selected from thegroup consisting of O, S, N and P; each of the C₁-C₁₅ alkyl group andthe C₃-C₁₈ cycloalkyl group may be joined to the nitrogen atom of—NR²³R²⁴ through a carbon atom; and at least one of R⁴, R⁵, R²³, and R²⁴may be a biomolecule, a linking group optionally joined to abiomolecule, or a group that may be substituted with at least onesubstituent that may be a biomolecule. In various embodiments, theC₁-C₁₅ alkyl group may be a C₁-C₆ alkyl group. In various embodiments,the C₃-C₁₈ cycloalkyl group may be a C₄-C₈ cycloalkyl group.

In various embodiments, the compound may be of the formula (IV):

wherein Q¹ may be —C≡CR⁸; and R⁸ may be as defined anywhere herein.

In an embodiment, R⁸ may be —N⁺R²⁵R²⁶R²⁷, —P⁺R²⁸R²⁹R³⁰, —S⁺R³¹R³²,NR³³R³⁴,

a biomolecule, a linking group optionally joined to a biomolecule, alinear or branched C₁-C₁₅ alkyl group or a C₃-C₁₈ cycloalkyl group,wherein each of the C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl groupmay be substituted with at least one substituent that may be abiomolecule and may be optionally intercepted with at least oneheteroatom selected from the group consisting of O, S, N and P; each ofthe C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl group may be joined tothe carbon atom of —C≡CR⁸ through a carbon atom; each of R²⁵, R²⁶, R²⁷,R²⁸, R²⁹, R³⁰, R³¹, R³², R³³, R³⁴, and R³⁵ may be as defined anywhereherein; and at least one of R⁸, R²⁵, R²⁶, R²⁷, R²⁸, R²⁹, R³⁰, R³¹, R³²,R³³, R³⁴, and R³⁵ may be a biomolecule, a linking group optionallyjoined to a biomolecule, or a group that may be substituted with atleast one substituent that may be a biomolecule, or forms a group thatis substituted with at least one substituent that is a biomolecule.

In various embodiments, R⁸ may be —N⁺R²⁵R²⁶R²⁷; each of R²⁵, R²⁶ and R²⁷may independently be H, D, a biomolecule, a linking group optionallyjoined to a biomolecule, a linear or branched C₁-C₁₅ alkyl group, or aC₃-C₁₈ cycloalkyl group, wherein each of the C₁-C₁₅ alkyl group and theC₃-C₁₈ cycloalkyl group may be unsubstituted or substituted and may beoptionally intercepted with at least one heteroatom selected from thegroup consisting of O, S, N and P; each of the C₁-C₁₅ alkyl group andthe C₃-C₁₈ cycloalkyl group may be joined to the nitrogen atom of—N⁺R²⁵R²⁶R²⁷ through a carbon atom, or R²⁵ may be absent and R²⁶ and R²⁷may be joined so that —N⁺R²⁵R²⁶R²⁷ forms a positively charged nitrogencontaining heterocyclic group which may be unsubstituted or substituted;and at least one of R²⁵, R²⁶ and R²⁷ may be a biomolecule, a linkinggroup optionally joined to a biomolecule, or a group that may besubstituted with at least one substituent that may be a biomolecule, orforms a group that is substituted with at least one substituent that isa biomolecule. In an embodiment, the positively charged 4 to 6-memberednitrogen containing heterocyclic group may be a pyridinium group, animidazolium group, a pyrazinium group, a pyrimidinium group or apyridazinium group, each of which may be substituted or unsubstituted.In various embodiments, the positively charged nitrogen containingheterocyclic group may be unsubstituted. In various embodiments, theC₁-C₁₅ alkyl group may be a C₁-C₆ alkyl group. In various embodiments,the C₃-C₁₈ cycloalkyl group may be a C₄-C₈ cycloalkyl group.

In various embodiments, R⁸ may be —P⁺R²⁸R²⁹R³⁰; each of R²⁸, R²⁹, andR³⁰ may independently be H, D, a biomolecule, a linking group optionallyjoined to a biomolecule, a linear or branched C₁-C₁₅ alkyl group, or aC₃-C₁₈ cycloalkyl group, wherein each of the C₁-C₁₅ alkyl group and theC₃-C₁₈ cycloalkyl group may be unsubstituted or substituted and may beoptionally intercepted with at least one heteroatom selected from thegroup consisting of O, S, N and P; each of the C₁-C₁₅ alkyl group andthe C₃-C₁₈ cycloalkyl group may be joined to the phosphorus atom of—P⁺R²⁸R²⁹R³⁰ through a carbon atom; and at least one of R²⁸, R²⁹ and R³⁰may be a biomolecule, a linking group optionally joined to abiomolecule, or a group that may be substituted with at least onesubstituent that may be a biomolecule. In various embodiments, theC₁-C₁₅ alkyl group may be a C₁-C₆ alkyl group. In various embodiments,the C₃-C₁₈ cycloalkyl group may be a C₄-C₈ cycloalkyl group.

In various embodiments, R⁸ may be —S⁺R³¹R³²; each of R³¹ and R³² mayindependently be H, D, a biomolecule, a linking group optionally joinedto a biomolecule, a linear or branched C₁-C₁₅ alkyl group, or a C₃-C₁₈cycloalkyl group, wherein each of the C₁-C₁₅ alkyl group and the C₃-C₁₈cycloalkyl group may be unsubstituted or substituted and may beoptionally intercepted with at least one heteroatom selected from thegroup consisting of O, S, N and P; each of the C₁-C₁₅ alkyl group andthe C₃-C₁₈ cycloalkyl group may be joined to the sulfur atom of—S⁺R³¹R³² through a carbon atom; and at least one of R³¹ and R³² may bea biomolecule, a linking group optionally joined to a biomolecule, or agroup that may be substituted with at least one substituent that may bea biomolecule. In various embodiments, the C₁-C₁₅ alkyl group may be aC₁-C₆ alkyl group. In various embodiments, the C₃-C₁₈ cycloalkyl groupmay be a C₄-C₈ cycloalkyl group.

In an embodiment, R⁸ may be —NR³³R³⁴; each of R³³ and R³⁴ mayindependently be H, D, a biomolecule, a linking group optionally joinedto a biomolecule, a linear or branched C₁-C₁₅ alkyl group, or a C₃-C₁₈cycloalkyl group, wherein each of the C₁-C₁₅ alkyl group and the C₃-C₁₈cycloalkyl group may be unsubstituted or substituted and may beoptionally intercepted with at least one heteroatom selected from thegroup consisting of O, S, N and P; each of the C₁-C₁₅ alkyl group andthe C₃-C₁₈ cycloalkyl group may be joined to the nitrogen atom of—NR³³R³⁴ through a carbon atom; and at least one of R³³ and R³⁴ may be abiomolecule, a linking group optionally joined to a biomolecule, or agroup that may be substituted with at least one substituent that may bea biomolecule. In various embodiments, the C₁-C₁₅ alkyl group may be aC₁-C₆ alkyl group. In various embodiments, the C₃-C₁₈ cycloalkyl groupmay be a C₄-C₈ cycloalkyl group.

In an embodiment, R⁸ may be

and R³⁵ may be a biomolecule, a linking group optionally joined to abiomolecule, a linear or branched C₁-C₁₅ alkyl group or a C₃-C₁₈cycloalkyl group, wherein each of the C₁-C₁₅ alkyl group and the C₃-C₁₈cycloalkyl group may be substituted with at least one substituent thatmay be a biomolecule and may be optionally intercepted with at least oneheteroatom selected from the group consisting of O, S, N and P; and eachof the C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl group may be joinedto the carbon atom of

through a carbon atom. In various embodiments, the C₁-C₁₅ alkyl groupmay be a C₁-C₆ alkyl group. In various embodiments, the C₃-C₁₈cycloalkyl group may be a C₄-C₈ cycloalkyl group.

In various embodiments, R⁸ may be a biomolecule, a linking groupoptionally joined to a biomolecule, a linear or branched C₁-C₁₅ alkylgroup, or a C₃-C₁₈ cycloalkyl group, wherein each of the C₁-C₁₅ alkylgroup and the C₃-C₁₈ cycloalkyl group may be substituted with at leastone substituent that may be a biomolecule and may be optionallyintercepted with at least one heteroatom selected from the groupconsisting of O, S, N and P; and each of the C₁-C₁₅ alkyl group and theC₃-C₁₈ cycloalkyl group may be joined to the carbon atom of —C═CR⁸through a carbon atom. In various embodiments, R⁸ may be a linear orbranched C₁-C₁₅ alkyl group or a C₃-C₁₈ cycloalkyl group, wherein eachof the C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl group may besubstituted with at least one substituent that may be a biomolecule andmay be optionally intercepted with at least one heteroatom selected fromthe group consisting of O, S, N and P; and each of the C₁-C₁₅ alkylgroup and the C₃-C₁₈ cycloalkyl group may be joined to the carbon atomof —C≡CR⁸ through a carbon atom. In various embodiments, R⁸ may be abiomolecule or a linking group optionally joined to a biomolecule. Invarious embodiments, the C₁-C₁₅ alkyl group may be a C₁-C₆ alkyl group.In various embodiments, the C₃-C₁₈ cycloalkyl group may be a C₄-C₈cycloalkyl group.

In an embodiment, the compound may be of the formula (IV):

wherein Q¹ may be

and R⁹ may be as defined anywhere herein.

In various embodiments, R⁹ may be —NR³⁸R³⁹,

a biomolecule, a linking group optionally joined to a biomolecule, alinear or branched C₁-C₁₅ alkyl group, or a C₃-C₁₈ cycloalkyl group,wherein each of the C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl groupmay be substituted with at least one substituent that may be abiomolecule and may be optionally intercepted with at least oneheteroatom selected from the group consisting of O, S, N and P; each ofthe C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl group may be joined tothe carbon atom of

through a carbon atom; each of R³⁸, R³⁹, and R⁴⁰ may be as definedanywhere herein; and at least one of R⁹, R³⁸, R³⁹, and R⁴⁰ may be abiomolecule, a linking group optionally joined to a biomolecule, or agroup that may be substituted with at least one substituent that may bea biomolecule. In various embodiments, the C₁-C₁₅ alkyl group may be aC₁-C₆ alkyl group. In various embodiments, the C₃-C₁₈ cycloalkyl groupmay be a C₄-C₈ cycloalkyl group.

In various embodiments, R⁹ may be —NR³⁸R³⁹; each of R³⁸ and R³⁹ mayindependently be H, D, a biomolecule, a linking group optionally joinedto a biomolecule, a linear or branched C₁-C₁₅ alkyl group, or a C₃-C₁₈cycloalkyl group, wherein each of the C₁-C₁₅ alkyl group and the C₃-C₁₈cycloalkyl group may be unsubstituted or substituted and may beoptionally intercepted with at least one heteroatom selected from thegroup consisting of O, S, N and P; each of the C₁-C₁₅ alkyl group andthe C₃-C₁₈ cycloalkyl group may be joined to the nitrogen atom of—NR³⁸R³⁹ through a carbon atom; and at least one of R³⁸ and R³⁹ may be abiomolecule, a linking group optionally joined to a biomolecule, or agroup that may be substituted with at least one substituent that may bea biomolecule. In various embodiments, the C₁-C₁₅ alkyl group may be aC₁-C₆ alkyl group. In various embodiments, the C₃-C₁₈ cycloalkyl groupmay be a C₄-C₈ cycloalkyl group.

In an embodiment, R⁹ may be

and R⁴⁰ may be a biomolecule, a linking group optionally joined to abiomolecule, a linear or branched C₁-C₁₅ alkyl group, or a C₃-C₁₈cycloalkyl group, wherein each of the C₁-C₁₅ alkyl group and the C₃-C₁₈cycloalkyl group may be substituted with at least one substituent thatmay be a biomolecule and may be optionally intercepted with at least oneheteroatom selected from the group consisting of O, S, N and P; and eachof the C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl group may be joinedto the carbon atom of

through a carbon atom. In various embodiments, the C₁-C₁₅ alkyl groupmay be a C₁-C₆ alkyl group. In various embodiments, the C₃-C₁₈cycloalkyl group may be a C₄-C₈ cycloalkyl group.

In various embodiments, R⁹ may be a biomolecule, a linking groupoptionally joined to a biomolecule, a linear or branched C₁-C₁₅ alkylgroup, or a C₃-C₁₈ cycloalkyl group, wherein each of the C₁-C₁₅ alkylgroup and the C₃-C₁₈ cycloalkyl group may be substituted with at leastone substituent that may be a biomolecule and may be optionallyintercepted with at least one heteroatom selected from the groupconsisting of O, S, N and P; and each of the C₁-C₁₅ alkyl group and theC₃-C₁₈ cycloalkyl group may be joined to the carbon atom of

through a carbon atom. In an embodiment, R⁹ may be a linear or branchedC₁-C₁₅ alkyl group, or a C₃-C₁₈ cycloalkyl group, wherein each of theC₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl group may be substitutedwith at least one substituent that may be a biomolecule and may beoptionally intercepted with at least one heteroatom selected from thegroup consisting of O, S, N and P; and each of the C₁-C₁₅ alkyl groupand the C₃-C₁₈ cycloalkyl group may be joined to the carbon atom of

through a carbon atom. In an embodiment, R⁹ may be a biomolecule or alinking group optionally joined to a biomolecule. In variousembodiments, the C₁-C₁₅ alkyl group may be a C₁-C₆ alkyl group. Invarious embodiments, the C₃-C₁₈ cycloalkyl group may be a C₄-C₈cycloalkyl group.

In various embodiments, the compound may be of the formula (IV):

wherein Q¹ may be —R¹⁰C═CR¹¹R¹²; and each of R¹⁰, R¹¹, and R¹² may be asdefined anywhere herein.

In various embodiments, each of R¹⁰, R¹¹, and R¹² may independently beH, D, F, Cl, Br, I, CX₃, —N⁺R⁴¹R⁴²R⁴³, —P⁺R⁴⁴R⁴⁵R⁴⁶, —S⁺R⁴⁷R⁴⁸, abiomolecule, a linking group optionally joined to a biomolecule, alinear or branched C₁-C₁₅ alkyl group, or a C₃-C₁₈ cycloalkyl group,wherein each of the C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl groupis unsubstituted or substituted and is optionally intercepted with atleast one heteroatom selected from the group consisting of O, S, N andP; each of the C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl group isjoined to the carbon atom of —R¹⁰C═CR¹¹R¹² through a carbon atom, andeach X is the same or different and is F, Cl, Br, or I; each of R⁴¹,R⁴², R⁴³, R⁴⁴, R⁴⁵, R⁴⁶, R⁴⁷, and R⁴⁸ may be as defined anywhere herein;at least one of R¹⁰, R¹¹, and R¹² may independently be F, Cl, Br, I,CX₃, —N⁺R⁴¹R⁴²R⁴³, —P⁺R⁴⁴R⁴⁵R⁴⁶, or —S⁺R⁴⁷R⁴⁸; and at least one of R¹⁰,R¹¹, R¹², R⁴¹, R⁴², R⁴³, R⁴⁴, R⁴⁵, R⁴⁶, R⁴⁷, and R⁴⁸ may be abiomolecule, a linking group optionally joined to a biomolecule, or agroup that is substituted with at least one substituent that may be abiomolecule, or forms a group that is substituted with at least onesubstituent that is a biomolecule. In various embodiments, at least twoof R¹⁰, R¹¹, and R¹² may independently be F, Cl, Br, I, or CX₃, or atleast one of R¹⁰, R¹¹, and R¹² may be —N⁺R⁴¹R⁴²R⁴³, —P⁺R⁴⁴R⁴⁵R⁴⁶, or—S⁺R⁴⁷R⁴⁸; and at least one of R¹⁰, R¹¹, R¹², R⁴¹, R⁴², R⁴³, R⁴⁴, R⁴⁵,R⁴⁶, R⁴⁷, and R⁴⁸ may be a biomolecule, a linking group optionallyjoined to a biomolecule, or a group that is substituted with at leastone substituent that may be a biomolecule, or forms a group that issubstituted with at least one substituent that is a biomolecule. Invarious embodiments, two of R¹⁰, R¹¹, and R¹² may independently be F,Cl, Br, I, or CX₃, or one of R¹⁰, R¹¹, and R¹² may be —N⁺R⁴¹R⁴²R⁴³,—P⁺R⁴⁴R⁴⁵R⁴⁶, or —S⁺R⁴⁷R⁴⁸; and at least one of R¹⁰, R¹¹, R¹², R⁴¹, R⁴²,R⁴³, R⁴⁴, R⁴⁵, R⁴⁶, R⁴⁷, and R⁴⁸ may be a biomolecule, a linking groupoptionally joined to a biomolecule, or a group that is substituted withat least one substituent that may be a biomolecule, or forms a groupthat is substituted with at least one substituent that is a biomolecule.In various embodiments, the C₁-C₁₅ alkyl group may be a C₁-C₆ alkylgroup. In various embodiments, the C₃-C₁₈ cycloalkyl group may be aC₄-C₈ cycloalkyl group.

In various embodiments, each of R¹⁰, R¹¹, and R¹² may independently beH, D, F, Cl, Br, I, CX₃, —N⁺R⁴¹R⁴²R⁴³, —P⁺R⁴⁴R⁴⁵R⁴⁶, a biomolecule, alinking group optionally joined to a biomolecule, a linear or branchedC₁-C₁₅ alkyl group, or a C₃-C₁₈ cycloalkyl group, wherein each of theC₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl group is unsubstituted orsubstituted and is optionally intercepted with at least one heteroatomselected from the group consisting of O, S, N and P; each of the C₁-C₁₅alkyl group and the C₃-C₁₈ cycloalkyl group is joined to the carbon atomof —R¹⁰C═CR¹¹R¹² through a carbon atom, and each X is the same ordifferent and is F, Cl, Br, or I; each of R⁴¹, R⁴², R⁴³, R⁴⁴, R⁴⁵, R⁴⁶,R⁴⁷, and R⁴⁸ may be as defined anywhere herein; at least one of R¹⁰,R¹¹, and R¹² may independently be F, Cl, Br, I, CX₃, —N⁺R⁴¹R⁴²R⁴³ or—P⁺R⁴⁴R⁴⁵R⁴⁶; and at least one of R¹⁰, R¹¹, R¹², R⁴¹, R⁴², R⁴³, R⁴⁴,R⁴⁵, and R⁴⁶ may be a biomolecule, a linking group optionally joined toa biomolecule, or a group that is substituted with at least onesubstituent that may be a biomolecule, or forms a group that issubstituted with at least one substituent that is a biomolecule. Invarious embodiments, at least two of R¹⁰, R¹¹, and R¹² may independentlybe F, Cl, Br, I, or CX₃, or at least one of R¹⁰, R¹¹, and R¹² may be—N⁺R⁴¹R⁴²R⁴³, or —P⁺R⁴⁴R⁴⁵R⁴⁶; and at least one of R¹⁰, R¹¹, R¹², R⁴¹,R⁴²R⁴³, R⁴⁴, R⁴⁵, and R⁴⁶ may be a biomolecule, a linking groupoptionally joined to a biomolecule, or a group that is substituted withat least one substituent that may be a biomolecule, or forms a groupthat is substituted with at least one substituent that is a biomolecule.In various embodiments, two of R¹⁰, R¹¹, and R¹² may independently be F,Cl, Br, I, or CX₃, or one of R¹⁰, R¹¹, and R¹² may be —N⁺R⁴¹R⁴²R⁴³, or—P⁺R⁴⁴R⁴⁵R⁴⁶; and at least one of R¹⁰, R¹¹, R¹², R⁴¹, R⁴², R⁴³, R⁴⁴,R⁴⁵, and R⁴⁶ may be a biomolecule, a linking group optionally joined toa biomolecule, or a group that is substituted with at least onesubstituent that may be a biomolecule, or forms a group that issubstituted with at least one substituent that is a biomolecule. Invarious embodiments, the C₁-C₁₅ alkyl group may be a C₁-C₆ alkyl group.In various embodiments, the C₃-C₁₈ cycloalkyl group may be a C₄-C₈cycloalkyl group.

In various embodiments, each of R¹⁰, R¹¹, and R¹² may independently beH, D, F, Cl, Br, I, CX₃, —N⁺R⁴¹R⁴²R⁴³, —S⁺R⁴⁷R⁴⁸, a biomolecule, alinking group optionally joined to a biomolecule, a linear or branchedC₁-C₁₅ alkyl group, or a C₃-C₁₈ cycloalkyl group, wherein each of theC₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl group is unsubstituted orsubstituted and is optionally intercepted with at least one heteroatomselected from the group consisting of O, S, N and P; each of the C₁-C₁₅alkyl group and the C₃-C₁₈ cycloalkyl group is joined to the carbon atomof —R¹⁰C═CR¹¹R¹² through a carbon atom, and each X is the same ordifferent and is F, Cl, Br, or I; each of R⁴¹, R⁴², R⁴³, R⁴⁷, and R⁴⁸may be as defined anywhere herein; at least one of R¹⁰, R¹¹, and R¹² mayindependently be F, Cl, Br, I, CX₃, —N⁺R⁴¹R⁴²R⁴³, or —S⁺R⁴⁷R⁴⁸ and atleast one of R¹⁰, R¹¹, R¹², R⁴¹, R⁴², R⁴³, R⁴⁷, and R⁴⁸ may be abiomolecule, a linking group optionally joined to a biomolecule, or agroup that is substituted with at least one substituent that may be abiomolecule, or forms a group that is substituted with at least onesubstituent that is a biomolecule. In various embodiments, at least twoof R¹⁰, R¹¹, and R¹² may independently be F, Cl, Br, I, or CX₃, or atleast one of R¹⁰, R¹¹, and R¹² may be —N⁺R⁴¹R⁴²R⁴³ or —S⁺R⁴⁷R⁴⁸; and atleast one of R¹⁰, R¹¹, R¹², R⁴¹, R⁴², R⁴³, R⁴⁷, and R⁴⁸ may be abiomolecule, a linking group optionally joined to a biomolecule, or agroup that is substituted with at least one substituent that may be abiomolecule, or forms a group that is substituted with at least onesubstituent that is a biomolecule. In various embodiments, two of R¹⁰,R¹¹, and R¹² may independently be F, Cl, Br, I, or CX₃, or one of R¹⁰,R¹¹, and R¹² may be —N⁺R⁴¹R⁴²R⁴³ or —S⁺R⁴⁷R⁴⁸; and at least one of R¹⁰,R¹¹, R¹², R⁴¹, R⁴², R⁴³, R⁴⁷, and R⁴⁸ may be a biomolecule, a linkinggroup optionally joined to a biomolecule, or a group that is substitutedwith at least one substituent that may be a biomolecule, or forms agroup that is substituted with at least one substituent that is abiomolecule. In various embodiments, the C₁-C₁₅ alkyl group may be aC₁-C₆ alkyl group. In various embodiments, the C₃-C₁₈ cycloalkyl groupmay be a C₄-C₈ cycloalkyl group.

In various embodiments, each of R¹⁰, R¹¹, and R¹² may independently beH, D, F, Cl, Br, I, CX₃, —P⁺R⁴⁴R⁴⁵R⁴⁶, —S⁺R⁴⁷R⁴⁸, a biomolecule, alinking group optionally joined to a biomolecule, a linear or branchedC₁-C₁₅ alkyl group, or a C₃-C₁₈ cycloalkyl group, wherein each of theC₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl group is unsubstituted orsubstituted and is optionally intercepted with at least one heteroatomselected from the group consisting of O, S, N and P; each of the C₁-C₁₅alkyl group and the C₃-C₁₈ cycloalkyl group is joined to the carbon atomof —R¹⁰C═CR¹¹R¹² through a carbon atom, and each X is the same ordifferent and is F, Cl, Br, or I; each of R⁴⁴, R⁴⁵, R⁴⁶, R⁴⁷, and R⁴⁸may be as defined anywhere herein; at least one of R¹⁰, R¹¹, and R¹² mayindependently be F, Cl, Br, I, CX₃, —P⁺R⁴⁴R⁴⁵R⁴⁶, or —S⁺R⁴⁷R⁴⁸ and atleast one of R¹⁰, R¹¹, R¹², R⁴⁴, R⁴⁵, R⁴⁶, R⁴⁷, and R⁴⁸ may be abiomolecule, a linking group optionally joined to a biomolecule, or agroup that is substituted with at least one substituent that may be abiomolecule, or forms a group that is substituted with at least onesubstituent that is a biomolecule. In various embodiments, at least twoof R¹⁰, R¹¹, and R¹² may independently be F, Cl, Br, I, or CX₃, or atleast one of R¹⁰, R¹¹, and R¹² may be —P⁺R⁴⁴R⁴⁵R⁴⁶ or —S⁺R⁴⁷R⁴⁸; and atleast one of R¹⁰, R¹¹, R¹², R⁴⁴, R⁴⁵, R⁴⁶, R⁴⁷, and R⁴⁸ may be abiomolecule, a linking group optionally joined to a biomolecule, or agroup that is substituted with at least one substituent that may be abiomolecule, or forms a group that is substituted with at least onesubstituent that is a biomolecule. In various embodiments, two of R¹⁰,R¹¹, and R¹² may independently be F, Cl, Br, I, or CX₃, or one of R¹⁰,R¹¹, and R¹² may be —P⁺R⁴⁴R⁴⁵R⁴⁶ or —S⁺R⁴⁷R⁴⁸; and at least one of R¹⁰,R¹¹, R¹², R⁴⁴, R⁴⁵, R⁴⁶, R⁴⁷, and R⁴⁸ may be a biomolecule, a linkinggroup optionally joined to a biomolecule, or a group that is substitutedwith at least one substituent that may be a biomolecule, or forms agroup that is substituted with at least one substituent that is abiomolecule. In various embodiments, the C₁-C₁₅ alkyl group may be aC₁-C₆ alkyl group. In various embodiments, the C₃-C₁₈ cycloalkyl groupmay be a C₄-C₈ cycloalkyl group.

In various embodiments, each of R¹⁰, R¹¹, and R¹² may independently beH, D, —N⁺R⁴¹R⁴²R⁴³, —P⁺R⁴⁴R⁴⁵R⁴⁶, —S⁺R⁴⁷R⁴⁸, a biomolecule, a linkinggroup optionally joined to a biomolecule, a linear or branched C₁-C₁₅alkyl group, or a C₃-C₁₈ cycloalkyl group, wherein each of the C₁-C₁₅alkyl group and the C₃-C₁₈ cycloalkyl group is unsubstituted orsubstituted and is optionally intercepted with at least one heteroatomselected from the group consisting of O, S, N and P; each of the C₁-C₁₅alkyl group and the C₃-C₁₈ cycloalkyl group is joined to the carbon atomof —R¹⁰C═CR¹¹R¹² through a carbon atom; each of R⁴¹, R⁴², R⁴³, R⁴⁴, R⁴⁵,R⁴⁶, R⁴⁷, and R⁴⁸ may be as defined anywhere herein; at least one ofR¹⁰, R¹¹, and R¹² may independently be —N⁺R⁴¹R⁴²R⁴³, —P⁺R⁴⁴R⁴⁵R⁴⁶, or—S⁺R⁴⁷R⁴⁸; and at least one of R¹⁰, R¹¹, R¹², R⁴¹, R⁴², R⁴³, R⁴⁴, R⁴⁵,R⁴⁶, R⁴⁷, and R⁴⁸ may be a biomolecule, a linking group optionallyjoined to a biomolecule, or a group that is substituted with at leastone substituent that may be a biomolecule, or forms a group that issubstituted with at least one substituent that is a biomolecule. Invarious embodiments, one of R¹⁰, R¹¹, and R¹² may be —N⁺R⁴¹R⁴²R⁴³,—P⁺R⁴⁴R⁴⁵R⁴⁶, or —S⁺R⁴⁷R⁴⁸; and at least one of R¹⁰, R¹¹, R¹², R⁴¹, R⁴²,R⁴³, R⁴⁴, R⁴⁵, R⁴⁶, R⁴⁷ and R⁴⁸ may be a biomolecule, a linking groupoptionally joined to a biomolecule, or a group that is substituted withat least one substituent that may be a biomolecule, or forms a groupthat is substituted with at least one substituent that is a biomolecule.In various embodiments, the C₁-C₁₅ alkyl group may be a C₁-C₆ alkylgroup. In various embodiments, the C₃-C₁₈ cycloalkyl group may be aC₄-C₈ cycloalkyl group.

In various embodiments, each of R¹⁰, R¹¹, and R¹² may independently beH, D, F, Cl, Br, I, CX₃, —N⁺R⁴¹R⁴²R⁴³, a biomolecule, a linking groupoptionally joined to a biomolecule, a linear or branched C₁-C₁₅ alkylgroup, or a C₃-C₁₈ cycloalkyl group, wherein each of the C₁-C₁₅ alkylgroup and the C₃-C₁₈ cycloalkyl group is unsubstituted or substitutedand is optionally intercepted with at least one heteroatom selected fromthe group consisting of O, S, N and P; each of the C₁-C₁₅ alkyl groupand the C₃-C₁₈ cycloalkyl group is joined to the carbon atom of—R¹⁰C═CR¹¹R¹² through a carbon atom, and each X is the same or differentand is F, Cl, Br, or I; each of R⁴¹, R⁴², and R⁴³ may be as definedanywhere herein; at least one of R¹⁰, R¹¹, and R¹² may independently beF, Cl, Br, I, CX₃, or —N⁺R⁴¹R⁴²R⁴³; and at least one of R¹⁰, R¹¹, R¹²,R⁴¹, R⁴², and R⁴³ may be a biomolecule, a linking group optionallyjoined to a biomolecule, or a group that is substituted with at leastone substituent that may be a biomolecule, or forms a group that issubstituted with at least one substituent that is a biomolecule. Invarious embodiments, at least two of R¹⁰, R¹, and R¹² may independentlybe F, Cl, Br, I, or CX₃, or at least one of R¹⁰, R¹¹, and R¹² may be—N⁺R⁴¹R⁴²R⁴³; and at least one of R¹⁰, R¹¹, R¹², R⁴¹, R⁴², and R⁴³ maybe a biomolecule, a linking group optionally joined to a biomolecule, ora group that is substituted with at least one substituent that may be abiomolecule, or forms a group that is substituted with at least onesubstituent that is a biomolecule. In various embodiments, two of R¹⁰,R¹¹, and R¹² may independently be F, Cl, Br, I, or CX₃, or one of R¹⁰,R¹¹, and R¹² may be —N⁺R⁴¹R⁴²R⁴³; and at least one of R¹⁰, R¹¹, R¹²,R⁴¹, R⁴², and R⁴³ may be a biomolecule, a linking group optionallyjoined to a biomolecule, or a group that is substituted with at leastone substituent that may be a biomolecule, or forms a group that issubstituted with at least one substituent that is a biomolecule. Invarious embodiments, the C₁-C₁₅ alkyl group may be a C₁-C₆ alkyl group.In various embodiments, the C₃-C₁₈ cycloalkyl group may be a C₄-C₈cycloalkyl group.

In various embodiments, each of R¹⁰, R¹¹, and R¹² may independently beH, D, F, Cl, Br, I, CX₃, —P⁺R⁴⁴R⁴⁵R⁴⁶, a biomolecule, a linking groupoptionally joined to a biomolecule, a linear or branched C₁-C₁₅ alkylgroup, or a C₃-C₁₈ cycloalkyl group, wherein each of the C₁-C₁₅ alkylgroup and the C₃-C₁₈ cycloalkyl group is unsubstituted or substitutedand is optionally intercepted with at least one heteroatom selected fromthe group consisting of O, S, N and P; each of the C₁-C₁₅ alkyl groupand the C₃-C₁₈ cycloalkyl group is joined to the carbon atom of—R¹⁰C═CR¹¹R¹² through a carbon atom, and each X is the same or differentand is F, Cl, Br, or I; each of R⁴, R⁴⁵, and R⁴⁶ may be as definedanywhere herein; at least one of R¹⁰, R¹¹, and R¹² may independently beF, Cl, Br, I, CX₃, or —P⁺R⁴⁴R⁴⁵R⁴⁶; and at least one of R¹⁰, R¹¹, R¹²,R⁴⁴, R⁴⁵, and R⁴⁶ may be a biomolecule, a linking group optionallyjoined to a biomolecule, or a group that is substituted with at leastone substituent that may be a biomolecule. In various embodiments, atleast two of R¹⁰, R¹¹, and R¹² may independently be F, Cl, Br, I, orCX₃, or at least one of R¹⁰, R¹¹, and R¹² may be —P⁺R⁴⁴R⁴⁵R⁴⁶; and atleast one of R¹⁰, R¹¹, R¹², R⁴⁴, R⁴⁵, and R⁴⁶ may be a biomolecule, alinking group optionally joined to a biomolecule, or a group that issubstituted with at least one substituent that may be a biomolecule. Invarious embodiments, two of R¹⁰, R¹¹, and R¹² may independently be F,Cl, Br, I, or CX₃, or one of R¹⁰, R¹¹, and R¹² may be —P⁺R⁴⁴R⁴⁵R⁴⁶; andat least one of R¹⁰, R¹¹, R¹², R⁴⁴, R⁴⁵, and R⁴⁶ may be a biomolecule, alinking group optionally joined to a biomolecule, or a group that issubstituted with at least one substituent that may be a biomolecule. Invarious embodiments, the C₁-C₁₅ alkyl group may be a C₁-C₆ alkyl group.In various embodiments, the C₃-C₁₈ cycloalkyl group may be a C₄-C₈cycloalkyl group.

In various embodiments, each of R¹⁰, R¹¹, and R¹² may independently beH, D, F, Cl, Br, I, CX₃, —S⁺R⁴⁷R⁴⁸, a biomolecule, a linking groupoptionally joined to a biomolecule, a linear or branched C₁-C₁₅ alkylgroup, or a C₃-C₁₈ cycloalkyl group, wherein each of the C₁-C₁₅ alkylgroup and the C₃-C₁₈ cycloalkyl group is unsubstituted or substitutedand is optionally intercepted with at least one heteroatom selected fromthe group consisting of O, S, N and P; each of the C₁-C₁₅ alkyl groupand the C₃-C₁₈ cycloalkyl group is joined to the carbon atom of—R¹⁰C═CR¹¹R¹² through a carbon atom, and each X is the same or differentand is F, Cl, Br, or I; each of R⁴⁷ and R⁴⁸ may be as defined anywhereherein; at least one of R¹⁰, R¹¹, and R¹² may independently be F, Cl,Br, I, CX₃, or —S⁺R⁴⁷R⁴⁸; and at least one of R¹⁰, R¹¹, R¹², R⁴⁷, andR⁴⁸ may be a biomolecule, a linking group optionally joined to abiomolecule, or a group that is substituted with at least onesubstituent that may be a biomolecule. In various embodiments, at leasttwo of R¹⁰, R¹¹, and R¹² may independently be F, Cl, Br, I, or CX₃, orat least one of R¹⁰, R¹¹, and R¹² may be —S⁺R⁴⁷R⁴⁸; and at least one ofR¹⁰, R¹¹, R¹², R⁴⁷, and R⁴⁸ may be a biomolecule, a linking groupoptionally joined to a biomolecule, or a group that is substituted withat least one substituent that may be a biomolecule. In variousembodiments, at two of R¹⁰, R¹¹, and R¹² may independently be F, Cl, Br,I, or CX₃, or one of R¹⁰, R¹¹, and R¹² may be —S⁺R⁴⁷R⁴⁸; and at leastone of R¹⁰, R¹¹, R¹², R⁴⁷, and R⁴⁸ may be a biomolecule, a linking groupoptionally joined to a biomolecule, or a group that is substituted withat least one substituent that may be a biomolecule. In variousembodiments, the C₁-C₁₅ alkyl group may be a C₁-C₆ alkyl group. Invarious embodiments, the C₃-C₁₈ cycloalkyl group may be a C₄-C₈cycloalkyl group.

In various embodiments, each of R¹⁰, R¹¹, and R¹² may independently beH, D, —N⁺R⁴¹R⁴²R⁴³, —P+R⁴⁴R⁴⁵R⁴⁶, a biomolecule, a linking groupoptionally joined to a biomolecule, a linear or branched C₁-C₁₅ alkylgroup, or a C₃-C₁₈ cycloalkyl group, wherein each of the C₁-C₁₅ alkylgroup and the C₃-C₁₈ cycloalkyl group is unsubstituted or substitutedand is optionally intercepted with at least one heteroatom selected fromthe group consisting of O, S, N and P; each of the C₁-C₁₅ alkyl groupand the C₃-C₁₈ cycloalkyl group is joined to the carbon atom of—R¹⁰C═CR¹¹R¹² through a carbon atom; each of R⁴¹, R⁴², R⁴³, R⁴⁴, R⁴⁵,and R⁴⁶ may be as defined anywhere herein; at least one of R¹⁰, R¹¹, andR¹² may independently be —N⁺R⁴¹R⁴²R⁴³ or —P⁺R⁴⁴R⁴⁵R⁴⁶; and at least oneof R¹⁰, R¹¹, R¹², R⁴¹, R⁴², R⁴³, R⁴⁴, R⁴⁵, and R⁴⁶ may be a biomolecule,a linking group optionally joined to a biomolecule, or a group that issubstituted with at least one substituent that may be a biomolecule, orforms a group that is substituted with at least one substituent that isa biomolecule. In various embodiments, one of R¹⁰, R¹¹, and R¹² may be—NR⁴¹R⁴²R⁴³ or —P⁺R⁴⁴R⁴⁵R⁴⁶; and at least one of R¹⁰, R¹¹, R¹², R⁴¹,R⁴², R⁴³, R⁴⁴, R⁴⁵, and R⁴⁶ may be a biomolecule, a linking groupoptionally joined to a biomolecule, or a group that is substituted withat least one substituent that may be a biomolecule, or forms a groupthat is substituted with at least one substituent that is a biomolecule.In various embodiments, the C₁-C₁₅ alkyl group may be a C₁-C₆ alkylgroup. In various embodiments, the C₃-C₁₈ cycloalkyl group may be aC₄-C₈ cycloalkyl group.

In various embodiments, each of R¹⁰, R¹¹, and R¹² may independently beH, D, —N⁺R⁴¹R⁴²R⁴³, —S⁺R⁴⁷R⁴⁸, a biomolecule, a linking group optionallyjoined to a biomolecule, a linear or branched C₁-C₁₅ alkyl group, or aC₃-C₁₈ cycloalkyl group, wherein each of the C₁-C₁₅ alkyl group and theC₃-C₁₈ cycloalkyl group is unsubstituted or substituted and isoptionally intercepted with at least one heteroatom selected from thegroup consisting of O, S, N and P; each of the C₁-C₁₅ alkyl group andthe C₃-C₁₈ cycloalkyl group is joined to the carbon atom of—R¹⁰C═CR¹¹R¹² through a carbon atom; each of R⁴¹, R⁴², R⁴³, R⁴⁷, and R⁴⁸may be as defined anywhere herein; at least one of R¹⁰, R¹¹, and R¹² mayindependently be —N⁺R⁴¹R⁴²R⁴³ or —S⁺R⁴⁷R⁴⁸; and at least one of R¹⁰,R¹¹, R¹², R⁴¹, R⁴², R⁴³, R⁴⁷, and R⁴⁸ may be a biomolecule, a linkinggroup optionally joined to a biomolecule, or a group that is substitutedwith at least one substituent that may be a biomolecule, or forms agroup that is substituted with at least one substituent that is abiomolecule. In various embodiments, one of R¹⁰, R¹¹, and R¹² may be—N⁺R⁴¹R⁴²R⁴³ or —S⁺R⁴⁷R⁴⁸; and at least one of R¹⁰, R¹¹, R², R⁴¹, R⁴²,R⁴³, R⁴⁷, and R⁴⁸ may be a biomolecule, a linking group optionallyjoined to a biomolecule, or a group that is substituted with at leastone substituent that may be a biomolecule, or forms a group that issubstituted with at least one substituent that is a biomolecule. Invarious embodiments, the C₁-C₁₅ alkyl group may be a C₁-C₆ alkyl group.In various embodiments, the C₃-C₁₈ cycloalkyl group may be a C₄-C₈cycloalkyl group.

In various embodiments, each of R¹⁰, R¹¹, and R¹² may independently beH, D, —P⁺R⁴⁴R⁴⁵R⁴⁶, —S⁺R⁴⁷R⁴⁸, a biomolecule, a linking group optionallyjoined to a biomolecule, a linear or branched C₁-C₁₅ alkyl group, or aC₃-C₁₈ cycloalkyl group, wherein each of the C₁-C₁₅ alkyl group and theC₃-C₁₈ cycloalkyl group is unsubstituted or substituted and isoptionally intercepted with at least one heteroatom selected from thegroup consisting of O, S, N and P; each of the C₁-C₁₅ alkyl group andthe C₃-C₁₈ cycloalkyl group is joined to the carbon atom of—R¹⁰C═CR¹¹R¹² through a carbon atom; each of R⁴⁴, R⁴⁵, R⁴⁶, R⁴⁷, and R⁴⁸may be as defined anywhere herein; at least one of R¹⁰, R¹¹, and R¹² mayindependently be —P⁺R⁴⁴R⁴⁵R⁴⁶ or —S⁺R⁴⁷R⁴⁸; and at least one of R¹⁰,R¹¹, R¹², R⁴⁴, R⁴⁵, R⁴⁶, R⁴⁷, and R⁴⁸ may be a biomolecule, a linkinggroup optionally joined to a biomolecule, or a group that is substitutedwith at least one substituent that may be a biomolecule. In variousembodiments, one of R¹⁰, R¹¹, and R¹² may be —P⁺R⁴⁴R⁴⁵R⁴⁶ or —S⁺R⁴⁷R⁴⁸;and at least one of R¹⁰, R¹¹, R¹², R⁴, R⁴⁵, R⁴⁶, R⁴⁷, and R⁴⁸ may be abiomolecule, a linking group optionally joined to a biomolecule, or agroup that is substituted with at least one substituent that may be abiomolecule. In various embodiments, the C₁-C₁₅ alkyl group may be aC₁-C₆ alkyl group. In various embodiments, the C₃-C₁₈ cycloalkyl groupmay be a C₄-C₈ cycloalkyl group.

In various embodiments, each of R¹⁰, R¹¹, and R¹² may independently beH, D, F, Cl, Br, I, CX₃, a biomolecule, a linking group optionallyjoined to a biomolecule, a linear or branched C₁-C₁₅ alkyl group, or aC₃-C₁₈ cycloalkyl group, wherein each of the C₁-C₁₅ alkyl group and theC₃-C₁₈ cycloalkyl group is unsubstituted or substituted and isoptionally intercepted with at least one heteroatom selected from thegroup consisting of O, S, N and P; each of the C₁-C₁₅ alkyl group andthe C₃-C₁₈ cycloalkyl group is joined to the carbon atom of—R¹⁰C═CR¹⁰R¹² through a carbon atom, and each X is the same or differentand is F, Cl, Br, or I; at least one of R¹⁰, R¹¹, and R¹² mayindependently be F, Cl, Br, I, or CX₃; and at least one of R¹⁰, R¹¹, andR¹² may be a biomolecule, a linking group optionally joined to abiomolecule, or a group that is substituted with at least onesubstituent that may be a biomolecule. In various embodiments, two ofR¹⁰, R¹¹, and R¹² may independently be F, Cl, Br, I, or CX₃; and one ofR¹⁰, R¹¹, and R¹² may be a biomolecule, a linking group optionallyjoined to a biomolecule, or a group that is substituted with at leastone substituent that may be a biomolecule. In various embodiments, theC₁-C₁₅ alkyl group may be a C₁-C₆ alkyl group. In various embodiments,the C₃-C₁₈ cycloalkyl group may be a C₄-C₈ cycloalkyl group.

In various embodiments, each of R¹⁰, R¹¹, and R¹² may independently beH, D, —N⁺R⁴¹R⁴²R⁴³, a biomolecule, a linking group optionally joined toa biomolecule, a linear or branched C₁-C₁₅ alkyl group, or a C₃-C₁₈cycloalkyl group, wherein each of the C₁-C₁₅ alkyl group and the C₃-C₁₈cycloalkyl group is unsubstituted or substituted and is optionallyintercepted with at least one heteroatom selected from the groupconsisting of O, S, N and P; each of the C₁-C₁₅ alkyl group and theC₃-C₁₈ cycloalkyl group is joined to the carbon atom of —R¹⁰C═CR¹¹R¹²through a carbon atom; each of R⁴¹, R⁴², and R⁴³ may be as definedanywhere herein; at least one of R¹⁰, R¹¹, and R¹² may independently be—N⁺R⁴¹R⁴²R⁴³; and at least one of R¹⁰, R¹¹, R¹², R⁴¹, R⁴², and R⁴³ maybe a biomolecule, a linking group optionally joined to a biomolecule, ora group that is substituted with at least one substituent that may be abiomolecule, or forms a group that is substituted with at least onesubstituent that is a biomolecule. In various embodiments, one of R¹⁰,R¹¹, and R¹² may be —N⁺R⁴¹R⁴²R⁴³; and at least one of R¹⁰, R¹¹, R¹²,R⁴¹, R⁴², and R⁴³ may be a biomolecule, a linking group optionallyjoined to a biomolecule, or a group that is substituted with at leastone substituent that may be a biomolecule, or forms a group that issubstituted with at least one substituent that is a biomolecule. In anembodiment, the positively charged 4 to 6-membered nitrogen containingheterocyclic group may be a pyridinium group, an imidazolium group, apyrazinium group, a pyrimidinium group or a pyridazinium group, each ofwhich may be substituted or unsubstituted. In various embodiments, thepositively charged nitrogen containing heterocyclic group may beunsubstituted. In various embodiments, the C₁-C₁₅ alkyl group may be aC₁-C₆ alkyl group. In various embodiments, the C₃-C₁₈ cycloalkyl groupmay be a C₄-C₈ cycloalkyl group.

In various embodiments, each of R¹⁰, R¹¹, and R¹² may independently beH, D, —P⁺R⁴⁴R⁴⁵R⁴⁶, a biomolecule, a linking group optionally joined toa biomolecule, a linear or branched C₁-C₁₅ alkyl group, or a C₃-C₁₈cycloalkyl group, wherein each of the C₁-C₁₅ alkyl group and the C₃-C₁₈cycloalkyl group is unsubstituted or substituted and is optionallyintercepted with at least one heteroatom selected from the groupconsisting of O, S, N and P; each of the C₁-C₁₅ alkyl group and theC₃-C₁₈ cycloalkyl group is joined to the carbon atom of —R¹⁰C═CR¹¹R¹²through a carbon atom; each of R⁴⁴, R⁴⁵, and R⁴⁶ may be as definedanywhere herein; at least one of R¹⁰, R¹¹, and R¹² may independently be—P⁺R⁴⁴R⁴⁵R⁴⁶; and at least one of R¹⁰, R¹¹, R¹², R⁴⁴, R⁴⁵, and R⁴⁶ maybe a biomolecule, a linking group optionally joined to a biomolecule, ora group that is substituted with at least one substituent that may be abiomolecule. In various embodiments, one of R¹⁰, R¹¹, and R¹² may be—P⁺R⁴⁴R⁴⁵R⁴⁶; and at least one of R¹⁰, R¹¹, R¹², R⁴⁴, R⁴⁵, and R⁴⁶ maybe a biomolecule, a linking group optionally joined to a biomolecule, ora group that is substituted with at least one substituent that may be abiomolecule. In various embodiments, the C₁-C₁₅ alkyl group may be aC₁-C₆ alkyl group. In various embodiments, the C₃-C₁₈ cycloalkyl groupmay be a C₄-C₈ cycloalkyl group.

In various embodiments, each of R¹⁰, R¹¹, and R¹² may independently beH, D, —S⁺R⁴⁷R⁴⁸, a biomolecule, a linking group optionally joined to abiomolecule, a linear or branched C₁-C₁₅ alkyl group, or a C₃-C₁₈cycloalkyl group, wherein each of the C₁-C₁₅ alkyl group and the C₃-C₁₈cycloalkyl group is unsubstituted or substituted and is optionallyintercepted with at least one heteroatom selected from the groupconsisting of O, S, N and P; each of the C₁-C₁₅ alkyl group and theC₃-C₁₈ cycloalkyl group is joined to the carbon atom of —R¹⁰C═CR¹¹R¹²through a carbon atom; each of R⁴⁷ and R⁴⁸ may be as defined anywhereherein; at least one of R¹⁰, R¹¹, and R¹² may independently be—S⁺R⁴⁷R⁴⁸; and at least one of R¹⁰, R¹¹, R¹², R⁴⁷, and R⁴⁸ may be abiomolecule, a linking group optionally joined to a biomolecule, or agroup that is substituted with at least one substituent that may be abiomolecule. In various embodiments, one of R¹⁰, R¹¹, and R¹² may be—S⁺R⁴⁷R⁴⁸; and at least one of R¹⁰, R¹¹, R¹², R⁴⁷, and R⁴⁸ may be abiomolecule, a linking group optionally joined to a biomolecule, or agroup that is substituted with at least one substituent that may be abiomolecule. In various embodiments, the C₁-C₁₅ alkyl group may be aC₁-C₆ alkyl group. In various embodiments, the C₃-C₁₈ cycloalkyl groupmay be a C₄-C₈ cycloalkyl group.

The term ‘biomolecule’ as used herein refers to a biomolecule, or analogor derivative of a biomolecule, or other molecule that may be deliveredinto a human or animal in order to track or image distribution of thebiomolecule within a human or animal body or tissue via positronemission tomography. Examples are disclosed in WO 2005/077967. In someembodiments, a ‘biomolecule’ refers to any molecule of medical,physiological or scientific significance, analog or derivative thereofthat may be compatible with a biological system or which possessesbiological activity. Biomolecules may be delivered into a human oranimal and include biomolecules that become localized at particularplaces in the organism. Examples include sugars, amino acids, nucleicacids, nucleotides, nucleosides, peptide hormones (steroid andnonsteroid), antibodies, aptamers and oligonucleotides, proteins,peptides, oligonucleotides, lipids, hormones, drugs (synthetic drugs andnatural products), polysaccharides, liposomes, micelles, microsomes,magnetic particles, metal chelators, oligoribonucleotides,oligonucleotides and related analogs bearing modifications in thebackbone, nucleobase, or phosphate linker regions that enhance stabilityor modulate specificity, peptidomimetics, dendrimers, drug deliveryagents, nanotubes, fullerenes, virus particles, and other targetingmolecules (e.g. cancer targeting molecules). Specific examples include,but are not limited to, biotin, matrix mettaloprotease inhibitors suchas marimastat, insulin, somatostatin, somatotropin, somatomedin,adrenocorticotropic hormone, parathormone, follicle stimulating hormone,luteinizing hormone, epidermal growth factor, thyroid stimulatinghormone, thyroid stimulating hormone releasing hormone, luteinizinghormone releasing hormone, vasopressin, bombesin, endothelin,gonadotropins, gonadotropin releasing hormone, antiflamin I&II,NLE-antiflamin II, brain natriureitic peptide, calcitonin, corticotropinreleasing peptide, oxytocin, calpain inhibitor peptide, alpha-CGRP,corticotropin releasing factor, galanin, growth hormone releasingfactor, guanylin, alpha-helical corticotropin releasing factor, laminin,alpha-melanocyte stimulating hormone, platelet derived growth factor,neuromedin, neurotensin, pancreatic polypeptide, pentagastrin,peptide-YY, pituitary adenylate cyclase activating peptide, secretin,thyrotropin releasing hormone, urocortin, vasoactive intestinal peptide,vasopressin, vascular endothelial growth factor, apamin, bungarotoxin,calciceptin, charybdotoxin, cobrotoxin, conotoxin, dendrotoxin,melittin, neuropeptide-Y, imperatoxin, taycatoxin, annexin, inhibin,insulin-like growth factor, prolactin, melanin stimulating hormone,melanin concentrating hormone, substance-P, tachykinin, angiotensin,antibodies of general structural classes of IgG, IgM, IgE, IgA, as wellas single-chain, monoclonal, and recombinant forms used for current andanticipated imaging, diagnostic, and therapeutic applications. Specifictargets that can be recognized by antibodies comprise withoutlimitation: melanoma cell, melanoma specific antigen, myelin basicprotein, breast cancer specific tumor markers such as Her2-Neu andBrc-Abl, alpha-fetoprotein, human chorionic gonadotropin, prostatespecific antigen, prostate specific membrane antigen, epidermal growthfactor receptors, fibroblast growth factor receptor, insulin receptor.Other examples are antibodies approved for use in therapy such asHerceptin™ (Amgen), Erbitux™ (Imclone). Polymers containing nucleobasesand nucleotides including RNA, DNA, and PNAs and various syntheticderivatives thereof that reflect modification of the sugar,intemucleoside linkage (backbone) and nucleobase portions are alsocontemplated. Oligonucleotides that can be used for imaging, forexample: antisense oligonucleotides that target mRNA of genes implicatedin the disease state, siRNA or RNAi molecules that target mRNA via RNAsilencing, and aptamer structures which represent a diverse class offolded nucleic acid structures that target protein or glycoforms ofproteins or both, or folded RNA structures. Further examples areaptamers approved for clinical use or those intended for clinical anddiagnostic use such as Macugen™ (Eyetech) and aptamers that are used inthe context of surface arrayed aptamers for diagnostic purposes,oligosaccharides of both synthetic and natural origin that are found onthe surface of cellular receptors or can mimic the glycoforms ofcellular receptors and proteins. Other saccharide components insynthetic glycoforms are sialic acid, mannose, fucose,N-acetyl-glucosamine, N-acetyl-mannosamine, maltose, galactose andN-acetyl-galactosamine, small to mid-size molecular weight ligands forproteins comprise various classes of compounds, for example: porphyrins,lectins, lipids, steroids, barbiturates, taxanes, terpenes, terpenoids,canabinoids, opioids, nucleosides, purines, pyrimidines,heteroaromatics, quinolines, biogenic amines, amino acids,indole-alkaloids, topane alkaloids, statins, enzyme inhibitors,nonsteroidal anti-inflammatory agents, monosaccharides, folates,derivatives of folate, methotrexate, derivatives of methotrexate,trexates, vitamins, growth hormone, VEGF, EGF, an antibody, a breastcancer antigen specific antibody, a prostate cancer antigen specificantibody, a melanoma antigen specific antibody, a ligand, a RGD-motifligand recognizing a matrix metalloprotease, an aptamer, an aptamerrecognizing a cell surface protein, folic acid, a folic acid derivativeand a methotrexate. Tracer molecules used in this invention may beconjugated to a ligand such as a biomolecule that preferentiallyinteracts with a tissue type or cell type of interest. In someembodiments, a precursor substituted alkyl-boronic acid may bepre-conjugated to a biomolecule of interest and subsequently fluoridatedwhen needed in a one-step aqueous fluoridation reaction. A typicalreaction may occur in a buffered solution of KHF₂ where the ¹⁸F may begenerated in carrier free form and supplemented with carrier ¹⁹F eitherat the time of fluoridation or during a chase reaction, while in anothertypical reaction the ¹⁸F will be used in an isotope exchange reaction.In various embodiments, the biomolecule may be a sugar, a peptide, anucleic acid, a lipid, a steroid, a biogenic amine or derivative oranalog thereof. In various embodiments, the biomolecule may be ahormone, a drug, insulin, somatostatin, growth hormone, VEGF, EGF,bombesin, a gonadotropin, gonadotropin releasing hormone, corticotropinreleasing peptide, oxytocin, corticotropin releasing factor, growthhormone releasing factor, platelet derived growth factor, neurotensin,urocortin, vasoactive intestinal peptide, inhibin, insulin-like growthfactor, an antisense oligonucleotide that targets mRNA of a geneimplicated in the disease state, a siRNA or RNAi molecule that targetsmRNA via RNA silencing, an antibody, a breast cancer antigen specificantibody, a prostate cancer antigen specific antibody, a melanomaantigen specific antibody, a ligand, a RGD-motif ligand recognizing amatrix metalloprotease, an aptamer, an aptamer recognizing a cellsurface protein, folic acid, a folic acid derivative and a methotrexateor a derivative or analog thereof.

Linking groups may include aliphatic or aromatic moieties designed toinsulate the biomolecule from the boron atom by an appropriate distanceor to ensure that appropriate atoms are adjacent the boron atom tofacilitate the fluoridation process. Groups which facilitate subsequentaddition of a biomolecule are well known in the art and may includemoieties which readily form a bond to a selected biomolecule, a varietyof such groups being known in the art. These include thiol and aminereactive groups and other such groups which may be useful for joining acompound of this invention to functionalities on biomolecules includinghydroxide, carboxylic acid, amine, sulfhydryl groups, etc. Furthercontemplated herein may be the joining of a compound of this inventionto a biomolecule through other linkages involving what is known as“click chemistry” with examples that include reactions of tetrazineswith either strained alkenes or alkynes, or alkynes with azides eitherby metal-mediated catalysis or strain promotion. Alternatively, bondsother than covalent bonds are contemplated. Thus, groups, which providefor ionic, hydrophobic and other non-covalent linkages to a biomoleculeare contemplated. Exemplary linker groups for facilitating conjugationto a biomolecule include:

In various embodiments, n may be 1 or 2; and each Y¹ may independentlybe selected from the group consisting of R¹, ¹⁸F, and ¹⁹F. In variousembodiments, n may be 1 or 2. Each Y¹ may independently be selected fromthe group consisting of R¹, ¹⁸F, and ¹⁹F. In various embodiments, n maybe 2 and each Y¹ may independently be selected from the group consistingof R¹, ¹⁸F, and ¹⁹F. In various embodiments, n may be 2, and each Y¹ mayindependently be R¹ or ¹⁸F, each Y¹ may independently be R¹ or ¹⁹F, oreach Y¹ may independently be ¹⁸F or ¹⁹F. In various embodiments, n maybe 2, and each Y¹ may be R¹, each Y¹ may be ¹⁸F, or each Y¹ may be ¹⁹F.In various embodiments, n may be 1, and Y¹ may be R¹, ¹⁸F, or ¹⁹F.

In various embodiments, R¹ may be absent or present. In an embodiment,when R¹ is present, R¹ may be any non-interfering group with regard tofluoridation of B. In an embodiment, R¹ may be a linear or branchedC₁-C₁₅ alkyl group or a non-aromatic C₃-C₁₈ cycloalkyl group, whereineach of the C₁-C₁₅ alkyl group and the non-aromatic C₃-C₁₈ cycloalkylgroup is unsubstituted or substituted and is optionally intercepted withat least one heteroatom selected from the group consisting of O, S, Nand P. In an embodiment, the C₁-C₁₅ alkyl group or non-aromatic C₃-C₁₈cycloalkyl group may be intercepted with at least one heteroatom at ornear the attachment point to B. In particular embodiments, R¹ may be alinear or branched C₁-C₆ alkyl group or a non-aromatic C₃-C₈ cycloalkylgroup. In various embodiments, the C₁-C₁₅ alkyl group may be a C₁-C₆alkyl group. In various embodiments, the non-aromatic C₃-C₁₈ cycloalkylgroup may be a C₄-C₈ cycloalkyl group.

In various embodiments, Y² may independently be selected from the groupconsisting of R², ¹⁸F, and ¹⁹F. In an embodiment, Y² may independentlybe selected from the group consisting of R² and ¹⁸F. In an embodiment,Y² may independently be selected from the group consisting of R² and¹⁹F. In an embodiment, Y² may independently be selected from the groupconsisting of ¹⁸F and ¹⁹F. In various embodiments, Y² may be R². Invarious embodiments, Y² may be ¹⁸F. In various embodiments, Y² may be¹⁹F.

In various embodiments, R² may be absent or present. In an embodiment,when R² is present, R² may be any non-interfering group with regard tofluoridation of B. In an embodiment, R² may be a linear or branchedC₁-C₁₅ alkyl group or a non-aromatic C₃-C₁₈ cycloalkyl group, whereineach of the C₁-C₁₅ alkyl group and the non-aromatic C₃-C₁₈ cycloalkylgroup is unsubstituted or substituted and is optionally intercepted withat least one heteroatom selected from the group consisting of O, S, Nand P. In an embodiment, the C₁-C₁₅ alkyl group or non-aromatic C₃-C₁₈cycloalkyl group may be intercepted with at least one heteroatom at ornear the attachment point to B. In particular embodiments, R² may be alinear or branched C₁-C₆ alkyl group or a non-aromatic C₃-C₈ cycloalkylgroup. In various embodiments, the C₁-C₁₅ alkyl group may be a C₁-C₆alkyl group. In various embodiments, the non-aromatic C₃-C₁₈ cycloalkylgroup may be a C₄-C₈ cycloalkyl group.

In various embodiments, each of R¹ and R² may independently be a linearor branched C₁-C₁₅ alkyl group or a non-aromatic C₃-C₁₈ cycloalkylgroup, wherein each of the C₁-C₁₅ alkyl group and the non-aromaticC₃-C₁₈ cycloalkyl group is unsubstituted or substituted and isoptionally intercepted with at least one heteroatom selected from thegroup consisting of O, S, N and P. In various embodiments, the C₁-C₁₅alkyl group may be a C₁-C₆ alkyl group. In various embodiments, thenon-aromatic C₃-C₁₈ cycloalkyl group may be a C₄-C₈ cycloalkyl group.

In various embodiments, n may be 2; each Y¹ may independently be ¹⁸F or¹⁹F; Y² may be ¹⁸F or ¹⁹F; and at least one of (Y¹)_(n) and Y² may be¹⁸F.

In various embodiments, the a linear or branched C₁-C₁₅ alkyl group maybe a linear or branched saturated C₁-C₂ alkyl group, or a linear orbranched saturated C₁-C₃ alkyl group, or a linear or branched saturatedC₁-C₄ alkyl group, or a linear or branched saturated C₁-C₅ alkyl group,or a linear or branched saturated C₁-C₆ alkyl group, or a linear orbranched saturated C₁-C₇ alkyl group, or a linear or branched saturatedC₁-C₈ alkyl group, or a linear or branched saturated C₁-C₉ alkyl group,or a linear or branched saturated C₁-C₁₀ alkyl group, or a linear orbranched saturated C₁-C₁ alkyl group, or a linear or branched saturatedC₁-C₁₂ alkyl group, or a linear or branched saturated C₁-C₁₃ alkylgroup, or a linear or branched saturated C₁-C₁₄ alkyl group, or a linearor branched saturated C₁-C₁₅ alkyl group, or a linear or branchedsaturated C₁ alkyl group, or a linear or branched saturated C₂ alkylgroup, or a linear or branched saturated C₃ alkyl group, or a linear orbranched saturated C₄ alkyl group, or a linear or branched saturated C₅alkyl group, or a linear or branched saturated C₆ alkyl group, or alinear or branched saturated C₇ alkyl group, or a linear or branchedsaturated C₈ alkyl group, or a linear or branched saturated C₉ alkylgroup, or a linear or branched saturated C₁₀ alkyl group, or a linear orbranched saturated C₁₁ alkyl group, or a linear or branched saturatedC₁₂ alkyl group, or a linear or branched saturated C₁₃ alkyl group, or alinear or branched saturated C₁₄ alkyl group, or a linear or branchedsaturated C₁₅ alkyl group.

In various embodiments, the linear or branched C₁-C₁₅ alkyl group may bea linear or branched C₂-C₃ alkenyl group, or a linear or branched C₂-C₄alkenyl group, or a linear or branched C₂-C₅ alkenyl group, or a linearor branched C₂-C₆ alkenyl group, or a linear or branched C₂-C₇ alkenylgroup, or a linear or branched C₂-C₈ alkenyl group, or a linear orbranched C₂-C₉ alkenyl group, or a linear or branched C₂-C₁₀ alkenylgroup, or a linear or branched C₂-C₁₁ alkenyl group, or a linear orbranched C₂-C₁₂ alkenyl group, or a linear or branched C₂-C₁₃ alkenylgroup, or a linear or branched C₂-C₁₄ alkenyl group, or a linear orbranched C₂-C₁₅ alkenyl group, or a linear or branched C₂ alkenyl group,or a linear or branched C₃ alkenyl group, or a linear or branched C₄alkenyl group, or a linear or branched C₅ alkenyl group, or a linear orbranched C₆ alkenyl group, or a linear or branched C₇ alkenyl group, ora linear or branched C₈ alkenyl group, or a linear or branched C₉alkenyl group, or a linear or branched C₁₀ alkenyl group, or a linear orbranched C₁₁ alkenyl group, or a linear or branched C₁₂ alkenyl group,or a linear or branched C₁₃ alkenyl group, or a linear or branched C₁₄alkenyl group, or a linear or branched C₁₅ alkenyl group.

In various embodiments, the linear or branched C₁-C₁₅ alkyl group may bea linear or branched C₂-C₃ alkynyl group, or a linear or branched C₂-C₄alkynyl group, or a linear or branched C₂-C₅ alkynyl group, or a linearor branched C₂-C₆ alkynyl group, or a linear or branched C₂-C₇ alkynylgroup, or a linear or branched C₂-C₈ alkynyl group, or a linear orbranched C₂-C₉ alkynyl group, or a linear or branched C₂-C₁₀ alkynylgroup, or a linear or branched C₂-C₁₁ alkynyl group, or a linear orbranched C₂-C₁₂ alkynyl group, or a linear or branched C₂-C₁₃ alkynylgroup, or a linear or branched C₂-C₁₄ alkynyl group, or a linear orbranched C₂-C₁₅ alkynyl group, or a linear or branched C₂ alkynyl group,or a linear or branched C₃ alkynyl group, or a linear or branched C₄alkynyl group, or a linear or branched C₅ alkynyl group, or a linear orbranched C₆ alkynyl group, or a linear or branched C₇ alkynyl group, ora linear or branched C₈ alkynyl group, or a linear or branched C₉alkynyl group, or a linear or branched C₁₀ alkynyl group, or a linear orbranched C₁₁ alkynyl group, or a linear or branched C₁₂ alkynyl group,or a linear or branched C₁₃ alkynyl group, or a linear or branched C₁₄alkynyl group, or a linear or branched C₁₅ alkynyl group.

In various embodiments, the C₃-C₁₈ cycloalkyl group may be a C₃-C₄cycloalkyl group, or a C₃-C₅ cycloalkyl group, or a C₃-C₆ cycloalkylgroup, or a C₃-C₇ cycloalkyl group, or a C₃-C₈ cycloalkyl group, or aC₃-C₉ cycloalkyl group, or a C₃-C₁₀ cycloalkyl group, or a C₃-C₁₁cycloalkyl group, or a C₃-C_(L2) cycloalkyl group, or a C₃-C₁₃cycloalkyl group, or a C₃-C₁₄ cycloalkyl group, or a C₃-C₁₅ cycloalkylgroup, or a C₃-C₁₆ cycloalkyl group, or a C₃-C₁₇ cycloalkyl group, or aC₃-C₁₈ cycloalkyl group, or a C₄-C₅ cycloalkyl group, or a C₄-C₆cycloalkyl group, or a C₄-C₇ cycloalkyl group, or a C₄-C₈ cycloalkylgroup, or a C₄-C₉ cycloalkyl group, or a C₄-C₁₀ cycloalkyl group, or aC₄-C₁₁ cycloalkyl group, or a C₄-C₁₂ cycloalkyl group, or a C₄-C₁₃cycloalkyl group, or a C₄-C₁₄ cycloalkyl group, or a C₄-C₁₅ cycloalkylgroup, or a C₄-C₁₆ cycloalkyl group, or a C₄-C₁₇ cycloalkyl group, or aC₄-C₁₈ cycloalkyl group, or a C₃ cycloalkyl group, or a C₄ cycloalkylgroup, or a C₅ cycloalkyl group, or a C₆ cycloalkyl group, or a C₇cycloalkyl group, or a C₈ cycloalkyl group, or a C₉ cycloalkyl group, ora C₁₀ cycloalkyl group, or a C₁₁ cycloalkyl group, or a C₁₂ cycloalkylgroup, or a C₁₃ cycloalkyl group, or a C₁₄ cycloalkyl group, or a C₁₅cycloalkyl group, or a C₁₆ cycloalkyl group, or a C₁₇ cycloalkyl group,or a C₁₈ cycloalkyl group.

In various embodiments, the C₃-C₁₈ cycloalkyl group may be a C₃-C₄cycloalkenyl group, or a C₃-C₅ cycloalkenyl group, or a C₃-C₆cycloalkenyl group, or a C₃-C₇ cycloalkenyl group, or a C₃-C₈cycloalkenyl group, or a C₃-C₉ cycloalkenyl group, or a C₃-C₁₀cycloalkenyl group, or a C₃-C₁₁ cycloalkenyl group, or a C₃-C₁₂cycloalkenyl group, or a C₃-C₁₃ cycloalkenyl group, or a C₃-C₁₄cycloalkenyl group, or a C₃-C₁₅ cycloalkenyl group, or a C₃-C₁₆cycloalkenyl group, or a C₃-C₁₇ cycloalkenyl group, or a C₃-C₁₈cycloalkenyl group, or a C₄-C₅ cycloalkenyl group, or a C₄-C₆cycloalkenyl group, or a C₄-C₇ cycloalkenyl group, or a C₄-C₈cycloalkenyl group, or a C₄-C₉ cycloalkenyl group, or a C₄-C₁₀cycloalkenyl group, or a C₄-C₁₁ cycloalkenyl group, or a C₄-C₁₂cycloalkenyl group, or a C₄-C₁₃ cycloalkenyl group, or a C₄-C₁₄cycloalkenyl group, or a C₄-C₁₅ cycloalkenyl group, or a C₄-C₁₆cycloalkenyl group, or a C₄-C₁₇ cycloalkenyl group, or a C₄-C₁₈cycloalkenyl group, or a C₃ cycloalkenyl group, or a C₄ cycloalkenylgroup, or a C₅ cycloalkenyl group, or a C₆ cycloalkenyl group, or a C₇cycloalkenyl group, or a C₈ cycloalkenyl group, or a C₉ cycloalkenylgroup, or a C₁₀ cycloalkenyl group, or a C₁₁ cycloalkenyl group, or aC₁₂ cycloalkenyl group, or a C₁₃ cycloalkenyl group, or a C₁₄cycloalkenyl group, or a C₁₅ cycloalkenyl group, or a C₁₆ cycloalkenylgroup, or a C₁₇ cycloalkenyl group, or a C₁₈ cycloalkenyl group.

In various embodiments, the C₃-C₁₈ cycloalkyl group may be a C₃-C₄cycloalkynyl group, or a C₃-C₅ cycloalkynyl group, or a C₃-C₆cycloalkynyl group, or a C₃-C₇ cycloalkynyl group, or a C₃-C₈cycloalkynyl group, or a C₃-C₉ cycloalkynyl group, or a C₃-C₁₀cycloalkynyl group, or a C₃-C₁₁ cycloalkynyl group, or a C₃-C₁₂cycloalkynyl group, or a C₃-C₁₃ cycloalkynyl group, or a C₃-C₁₄cycloalkynyl group, or a C₃-C₁₅ cycloalkynyl group, or a C₃-C₁₆cycloalkynyl group, or a C₃-C₁₇ cycloalkynyl group, or a C₃-C₁₈cycloalkynyl group, or a C₄-C₅ cycloalkynyl group, or a C₄-C₆cycloalkynyl group, or a C₄-C₇ cycloalkynyl group, or a C₄-C₈cycloalkynyl group, or a C₄-C₉ cycloalkynyl group, or a C₄-C₁₀cycloalkynyl group, or a C₄-C₁₁ cycloalkynyl group, or a C₄-C₁₂cycloalkynyl group, or a C₄-C₁₃ cycloalkynyl group, or a C₄-C₁₄cycloalkynyl group, or a C₄-C₁₅ cycloalkynyl group, or a C₄-C₁₆cycloalkynyl group, or a C₄-C₁₇ cycloalkynyl group, or a C₄-C₁₈cycloalkynyl group, or a C₃ cycloalkynyl group, or a C₄ cycloalkynylgroup, or a C₅ cycloalkynyl group, or a C₆ cycloalkynyl group, or a C₇cycloalkynyl group, or a C₈ cycloalkynyl group, or a C₉ cycloalkynylgroup, or a C₁₀ cycloalkynyl group, or a C₁₁ cycloalkynyl group, or aC₁₂ cycloalkynyl group, or a C₁₃ cycloalkynyl group, or a C₁₄cycloalkynyl group, or a C₁₅ cycloalkynyl group, or a C₁₆ cycloalkynylgroup, or a C₁₇ cycloalkynyl group, or a C₁₈ cycloalkynyl group.

In various embodiments, the linear or branched C₁-C₁₅ alkyl group or theC₃-C₁₈ cycloalkyl group may be intercepted with at least one heteroatomthat may independently be O, S, N or P; or S, N or P; or O, N or P; orO, S, or P; or O, S, or N; or N or P; or S or P; or S or N; or O or P;or O or N; or O or S; or P; or N; or S; or O.

In various embodiment, the C₁-C₁₅ alkyl group or the C₃-C₁₈ cycloalkylgroup may be substituted with one or more substituents selected from thegroup consisting of F, Cl, Br, I, —N⁺(C₁₋₁₅alkyl)₃, —N⁺(C₂₋₁₅alkenyl)₃,—N⁺(C₂₋₁₅alkynyl)₃, —N⁺H(C₁₋₁₅alkyl)₂, —N⁺H(C₂₋₁₅alkenyl)₂, —NH(C₂₋₁₅alkynyl)₂, P⁺(C₁₋₁₅alkyl)₃, P⁺(C₂₋₁₅alkenyl)₃, P⁺(C₂₋₁₅alkynyl)₃,S⁺(C₁₋₁₅alkyl)₂, S⁺(C₂₋₁₅alkenyl)₂, S⁺(C₂₋₁₅alkynyl)₂, oxo (i.e., ═O),—OC₁₋₁₅alkyl, unsubstituted or substituted aromatic C₃-C₁₈ cycloalkyl,unsubstituted or substituted non-aromatic C₃-C₁₈ heterocyclic group,unsubstituted or substituted aromatic C₃-C₁₈ heterocyclic group, ═NH,—C₁-C₁₅alkyl, non-aromatic C₃-C₁₈ cycloalkyl, —N(C₁₋₁₅alkyl)₂,—N(C₂₋₁₅alkenyl)₂, —N(C₂₋₁₅alkynyl)₂, —COOH, —NH₂, —SH, a biomolecule,and a linking group optionally joined to a biomolecule. In variousembodiments, the C₁-C₁₅ alkyl group or the C₃-C₁₈ cycloalkyl group maybe substituted with one or more substituents selected from the groupconsisting of F, Cl, Br, I, —N⁺(C₁₋₁₅alkyl)₃, —N⁺(C₂₋₁₅alkenyl)₃,—N⁺(C₂₋₁₅alkynyl)₃, —N⁺H(C₁₋₁₅alkyl)₂, —N⁺H(C₂₋₁₅alkenyl)₂,—NH(C₂₋₁₅alkynyl)₂, P⁺(C₁₋₁₅alkyl)₃, P⁺(C₂₋₁₅alkenyl)₃,P⁺(C₂₋₁₅alkynyl)₃, S⁺(C₁₋₁₅alkyl)₂, S⁺(C₂₋₁₅alkenyl)₂,S⁺(C₂₋₁₅alkynyl)₂, oxo (i.e., ═O), —OC₁₋₁₅alkyl, unsubstituted orsubstituted aromatic C₃-C₁₈ cycloalkyl, unsubstituted or substitutednon-aromatic C₃-C₁₈ heterocyclic group, unsubstituted or substitutedaromatic C₃-C₁₈ heterocyclic group, —C₁-C₁₅alkyl, non-aromatic C₃-C₁₈cycloalkyl, —N(C₁₋₁₅alkyl)₂, —N(C₂₋₁₅alkenyl)₂, —N(C₂₋₁₅alkynyl)₂,—COOH, —NH₂, —SH, a biomolecule, and a linking group optionally joinedto a biomolecule. In various embodiments, the C₁-C₁₅ alkyl group or theC₃-C₁₈ cycloalkyl group may be substituted with one or more substituentsselected from the group consisting of a biomolecule and a linking groupoptionally joined to a biomolecule.

The compounds may also include base-free forms, prodrugs, orpharmaceutically acceptable salts thereof. The compounds describedherein are meant to include all racemic mixtures and all individualenantiomers or combinations thereof, whether or not they are representedherein.

Various embodiments of the invention provide a method of making aprecursor compound which comprises converting a correspondingalkylboronic acid variant of any of the aforementioned compounds to analkylboronic ester, wherein one, two or three of Y¹ and Y² may be aleaving group displaceable by fluoride. This invention also provides amethod of making a ¹⁸F containing compound which comprises replacing atleast one of said leaving group or groups of the aforesaid alkylboronicester with ¹⁸F. Methods of this invention make use of substitutedalkyl-boronic compounds, wherein Y¹ or Y² may be a moiety that can bedisplaced by reaction with fluoride. These may be used as precursormolecules to the above-described ¹⁸F labeled alkyfluoroborate compoundsby reaction with a suitable source of ¹⁸F. In this aspect of theinvention, Y¹ or Y² may (for example) be an alkoxy, halide, amine (e.g.alkyl, aryl), or thiol (alkyl, aryl) moiety. Other examples of leavinggroups that can be displaced by fluoride are known. Particular examplesare described in WO 2005/077967.

Alkylfluoroborate compounds according to a formula described herein maybe made by a variety of synthetic methods, ranging in complexity from denovo synthesis to a ‘wash-in’ of the fluorine on a previously preparedboronate (see, for example, Molander et al., J. Org. Chem. 2010, 75,4304-4306; Lennox et al. JACS, 2012, 134, 7431-7441; Dumas et al.,Organic Letters, 2012, 14, 2138-2141; and Molander et al., OrganicLetters, 2006, 8, 2031-2034).

A ‘wash-in’ preparative method may include preparation of a solution ofa substituted alkylboronic acid or ester in an appropriate solvent, towhich aqueous fluoride is added. The pH may be at a suitable range (e.g.about 2.5 to about 3.5) or according to what is suitable for thesolvents and the substituted alkylboronic acid or ester. The solvent maybe DMF or another solvent that is miscible with an aqueous fluoridesolution, and solubilizes the substituted alkylboronic acid or ester ofinterest. Examples of such solvents may include aqueous mixturescomprising DMSO, DMF, MeOH, THF, MeCN, DMA, and NMP. Selection of aparticular solvent may vary with the particular substituted alkylboronicacid or ester and in particular with regards to preserving thebioactivity of the biomolecule, and is within the skill of one versed inthe art. Aqueous fluoride may be at any suitable concentration. Forexample, the substituted alkylboronic acid may be present at aconcentration of about 1-4 mM, and the KH^(18/19)F₂ may be present in 3or 4 equivalents i.e. 3-12 mM or 4-16 mM, where the minimalconcentrations are selected to increase the specific activity of thelabeling, and the maximal concentrations determined by the maximalsolubility of the bioconjugate.

Clinical preparations of a substituted alkylboronic acid or ester mayinvolve use of about 800 mCi ¹⁸F in no carrier added form, which,barring environmental contamination with ¹⁹F, represents about 0.46 nmolof ¹⁸F, or 3.8% of the total fluoride used in a 10 μL reaction at 12 mMtotal fluoride. Microreactor and microfluidic techniques, (which providereaction volumes of about 50 nL) can reduce the quantity of carrier ¹⁹Fneeded. For instance in a 50 nL reaction at 10 mM fluoride, one needsonly 500 pmol of total fluoride. Thus, a no carrier added reaction isreadily contemplated for labeling alkylboronic acids.

Reaction temperature may be increased above room temperature, but belowa temperature that may destabilize or denature the selected biomolecule.For example, some nucleic acids or oligonucleotides may be suitable foruse in labeling reactions at temperatures of about 60° C., while someproteins may require lower temperatures. Peptides are known to withstandtemperatures as high as about 110° C. Antibodies are known in the art tohave limited thermostability compared to most other proteins howeverthermostable antibodies and enzymes may also be suitable for use inlabeling reactions at temperatures above room temperature.Alternatively, some biomolecules may be preferentially suitable forlabeling reactions at reduced temperatures, i.e. below room temperature.

General approaches and methods for direct chemical modification ofbiomolecules for addition and/or substitution of modifying groups areknown. As an example, chemical modification of proteins is described byMeans and Feeney Bioconjugate Chemistry 1990 1: 2-12). Chemicalmodification of nucleic acids such as DNA and RNA is described in, forexample, Boutourine et al. Bioconjugate Chemistry 1990 1:350-56.Chemical modification of sugars and oligosaccharides is described in,for example Wood et al. Bioconjugate Chemistry 1992 3: 391-6 and morerecently in click reactions

In various embodiments, there is provided a method for selections orscreening substituted organotrifluoroborate compounds, for their abilityto resist defluoridation as an indicator of their longevity as a radioimaging agent for PET. Various methods may be employed such as describedbelow.

Chromatographic methods for separation of a fluoridated compound fromthe free ¹⁸F are useful for qualitative or semi-quantitative assessmentof the resistance to defluoridation of the fluoridated compound. Suchmethods generally involve a stationary phase, which may be a columnmatrix having qualities such as hydrophobicity, porosity orsize-exclusion capabilities, charge, hydrophilicity or the like.Alternately, the stationary phase may provide structural support only,and be largely inert to interactions with a mobile phase or the solutesin the mobile phase. The stationary phase may be further supported in,for example, a column, or for thin-layer chromatography, on a glassplate. Paper used in paper chromatography may provide both thestationary phase and physical support of the stationary phase.Alternatively a diol column can be used to remove unlabelled boronicacid that may be present as unreacted starting material or followingcompeting solvolysis of the organotrifluoroborate during labeling. Themobile phase is frequently a solvent, which may be hydrophobic orhydrophilic, aqueous or non-aqueous, and may be formulated to provide afixed pH or a selected pH range, or a particular salt or other soluteconcentration. In various embodiments, the molecules or compounds ofinterest, such as the fluoridated compounds above are soluble in themobile phase, as is the free fluorine that is to be separated from thefluoridated compound. Choice of a particular chromatographic method maybe influenced by the molecule to be separated. For example, separationof a labeled biomolecule, such as an antibody, gel-permeation oraffinity chromatography may be suitable. In another example, separationof a labeled oligonucleotide or peptide, anion exchange chromatographymay be suitable. In another example, separation of labeled biotincomplexed with an avidin-conjugate may involve gel-permeationchromatography. In another example, separation of labeled free biotin,folate or methotrexate or other small molecules, such as peptides mayinvolve chromatographic separation through a silica column or plug, orHPLC/FPLC.

General principles, methods and background relating to chromatographyare known, and may be found in, for example, Jonsson, J. A.Chromatographic Theory and Basic Principles. 1987. Marcel Dekker, orAhuja S. Chromatography and Separation Science. 2003. Elsevier Press;Cox, G. B. Preparative Enantioselective Chromatography. 2005. BlackwellPublishing; Wall, P. E. Thin-layer chromatography: a modern practicalapproach 205. Royal Society of Chemistry; Sherma, J. and Fried, B.Handbook of Thin-layer chromatography. 2003. Marcel Dekker.

¹⁹F-NMR may be also used to monitor defluoridation (e.g. see Ting et.al. (2008) J. Org. Chem. 73:4662-70; Hartwig et. al. (2008) TetrahedronLetters 49:3152-56; and, Ting et. al. (2008) Journal of FluorineChemistry 129:349-58).

Isotopic wash-out or pulse-chase methods may also be used for screeninglabeled trifluoroborates in order to identify compositions that aresuitably stable for use as imaging agents.

It is recognized that stable organotrifluoroborates (no ¹⁸Fincorporated) may be useful as radiochemically stable precursors thatwill find use in labeling whereby they are treated under acidicconditions to promote the exchange of an atom of ¹⁹F for an atom of ¹⁸F.Following labeling, at least one of F may be ¹⁸F. It may be recognizedthat in the preparation of compounds of this invention, that there maybe a fraction of molecules that will not be complexed with any ¹⁸F whencarrier ¹⁹F may be used. It may be recognized that the addition ofcarrier ¹⁹F may be advantageous in certain cases. A final/overallspecific activity suitable for imaging purposes can be achieved even ifa particular trifluoroborate molecule in a mixture contains no ¹⁸F,provided that at least some of the trifluoroborates prepared contain atleast one ¹⁸F.

Other aspects and features of the present invention will become apparentto those ordinarily skilled in the art upon review of the followingdescription of specific embodiments of the invention in conjunction withthe accompanying figures.

EXAMPLES

Aryltrifluoroborates undergo solvolysis (i. e., B—F bond scission) at anearly pH-independent rate above pH 3. The electronic nature of the ringsubstituents is the main factor affecting the rate of solvolysis. Groupson aryl rings impart their effects on rates by both inductive andresonance effects whereby the electron density in the pi-bonds isincreased or diminished. Increased pi electron density can delocalizefrom the ring into the sp2 orbital on boron to promote loss of onefluoride ion whereupon the other two are lost rapidly. Increasing theelectron density results in an enhancement of the rate of B—F bondscission, whereas decreasing the electron density reduces the rate. Theinductive effects are difficult to separate from those related toresonance, and both effects are further nuanced by whether thesubstituents are in the meta vs ortho/para positions. Moreover, it iscritical to understand the magnitude of these effects in order tounderstand how to create aryltrifluoroborates with sufficient stability.

The magnitude of these effects may be given by the ρ value in aquantitative linear free energy relationship. The effects ofsubstitution by several (at least two) electron withdrawing group may beestimated by summing their known σ values. The rate at which such acomposition reacts can be related to the rate of an unsubstitutedaryl-BF₃ by the following equation (log(k/k0)=σρ where k is thesolvolysis rate constant for a certain aryl-BF₃ under consideration andk0 is the solvolysis rate constant for an unsubstituted aryl-BF₃ Thus,for aryl-BF₃ solvolysis, the relationship between the rate of B—F bondscission and the number and position of various electron withdrawinggroups may be understood in terms of known a values and a value of ρ˜−1.Furthermore, owing to the change in the hybridization of boron from sp3to sp2 upon loss of a first fluoride ion, which places the remaining twofluorine atoms co-planar with the aryl ring, it has been recognized thatbulky ortho substituents may exert steric effects to retard solvolysis.

While aryl-trifluoroborate solvolysis can be understood in terms ofdelocalization of electron density from the arene pi-system into theempty p-orbital on boron with concomitant expulsion of a fluoride atomwhose rate is correlated by the Hammett relationship of (log(k/k0)=σρwhere ρ˜−1, this understanding based on a combination of inductiveeffects and pi-delocalization effects, as expressed in the pKa of (aryl)benzoic acids, and cannot be extended to substituted nonaromaticorganotrifluoroborates. Electron withdrawing groups can greatly affectthe rate of a reaction in some cases, but not in others, and thus theapplication of linear free energy relationships that hold well for arylsystems do not necessarily apply to nonaromatic compositions. It wasunclear to what extent such relationships could be extended to the rateof B—F bond scission in systems where the carbon atom to which the boronis attached is not in an aromatic state, and of what magnitude theseeffects would be.

Example 1 Fluoridation of a organoboronic Acid or Ester

22.4 mg (0.10 mmol) of N,N,-dimethyl-N-propargylammoniomethylboratepinacol ester was dissolved with 80 μL of DMF, then 2.4 equiv. 120 μL of3 M KHF₂ (aqueous solution) and 80 μL of 4 M HCl (aqueous solution) wereadded as the fluoridation reagents. This reaction was incubated at 37°C. for two hours, then it was concentrated with a vacuum concentrator(Speedvac). A yellowish white powder was achieved and was ready forfurther purification.

Example 2 Evaluation of Rates of Solvolytic Defluoridation ofFluoridated Organotrifluoroborates by 19F-Nuclear Magnetic Resonance(¹⁹F-NMR) Spectroscopy

The following is are representative examples of testing of solvolyticdefluoridation of fluoridated organoborates as shown in FIG. 1A to FIG.1FF and Table 1. Solutions of the fluoridated organotrifluoroborateswere made by dissolving 30 mg of the fluoridated organotrifluoroborateinto 1 mL of 20% ethanol/acetonitrile.

As the fluoridated organotrifluoroborate salts were often contaminatedwith a significant amount of free fluoride, a silica column was used toremove the free fluoride from the organotrifluoroborate solution. Afterloading the crude reaction onto the silica column, the fractionscontaining the desired organotrifluoroborate were eluted and combined toform a combined solution. In view of the strong stability of thefluoridated organotrifluoroborate in organic solvent, 20% of thecombined solution was stored in an NMR tube and this sample served asthe “zero” minute time point. A purified organotrifluoroborate salt wasisolated from the remaining portion of the combined solution (remaining80% of the combined solution) by removing the organic solvent from thecombined solution by vacuum. Removal of the organic solvent from thecombined solution gave the purified fluoridated alkylbornate salt in theform of a white solid. The dry and purified fluoridatedorganotrifluoroborate salt was re-dissolved into 3 mL of 200 mMphosphate buffer. Solvolytic defluoridation started immediately upondissolution of the fluoridated organotrifluoroborate salt into phosphatebuffer, and accordingly, the time was recorded at the moment ofdissolution. The progress of solvolytic defluoridation of thefluoridated organotrifluoroborate salt was monitored using ¹⁹F NMRspectroscopy. General principles, methods and background relating to theuse of ¹⁹F NMR spectroscopy for monitoring defluoridation are known, andmay be found in, for example, Ting et al. (2008, J. Org. Chem. 73;4662-70; Harwig et al. (2008) Tetrahedron Letters 49:3152-56; and Tinget al. (2008) Journal of Fluorine Chemistry 129:349-58. For each timepoint, solvolytic defluoridation data was collected using a 300 MHz ¹⁹FNMR spectrometer (Bruker). ¹⁹F NMR spectroscopic tracers for thefluoridated organotrifluoroborate salt at different times are shown inFIG. 1A. Use of ¹⁹F-NMR to measure solvolytic defluoridation provides auseful model for measuring solvolytic 18F-defluoridation because if oneF is lost, all are lost. Moreover, it is understood that the kineticisotope effect in terms of B—F bond solvolysis is negligible. Hencewhereas for PET scanning purposes solvolytic 18F-defluoridation is ofconsideration, ¹⁹F-NMR provides a reliable measure of the rate of18F-defluoridation since both ¹⁸F and ¹⁹F rates are the same in practicebecause there should be no measurable isotopic difference. The degree ofsolvolytic defluoridation of the fluoridated organotrifluoroborate saltwas plotted as a function of time, for example, as shown in FIG. 1B forCompound 6 of Table 1. ¹⁹F NMR spectroscopic tracers for the fluoridatedorganotrifluoroborate salts of compounds listed in Table 1 at differenttimes are shown in FIGS. 1A, 1C, 1E, 1G, 1I, 1K, 1M, 1O, 1Q, 1S, 1U, 1W,1Y, 1AA, 1CC, and 1EE, and the degree of solvolytic defluoridation ofthe compounds as a function of time is shown in FIGS. 1B, 1D, 1F, 1H,1J, 1L, 1N, 1P, 1R, 1T, 1V, 1X, 1ZZ, 1BB, 1DD, and 1FF. As can be seenfrom FIGS. 1B, 1D, 1F, 1H, 1J, 1L, 1N, 1P, 1R, 1T, 1V, 1X, 1ZZ, 1BB,1DD, and 1FF, solvolytic defluoridation of the fluoridated organoboratesalts shows pseudo first-order reaction kinetics.

Example 3 Rate Constant for Solvolytic Defluoridation

The time curves shown in FIGS. 1B and 1D were fitted and a rateconstant, k_(sovolysis), for each time curve was calculated. As ameasure of the stability of the fluoridated organoborate to solvolyticdefluoridation, pk_(B—F) values were calculated using the equationpk_(B—F)=−log(k_(solvolysis)). In addition to pk_(B—F) values, observedsolvolytic defluoridation half-life, t_(1/2), values and rate constants,k_(solvolysis), for a number of different fluoridated organoborates arelisted in Table 1. As can be seen from Table 1, the larger the pk_(B—F)value, the more stable the fluoridated organoborate was observed to beto solvolytic defluoridation.

TABLE 1 Rate Constant Data for Solvolytic Defluoridation of FluoridatedOrganoborate Compounds pKa of k(solvolysis) half-life, CompoundCorresponding pk(solvolysis) = −log in units of t ½ No. Structure COOH†k(solvolysis) min − 1 (min.) 1

4.81 0.52 0.3 2.3-3 2

4.25 1.01 0.099 7 3

3.53 2.32 0.00476 145 4

2.86 2.98 0.000768 658 5

2.5 3.5249 0.000298 2311 6

2.34 3.7554 0.000175 3929 7

2.45 3.7409 0.000181 3800 8

2.35 4.0700 8.52 × 10⁻⁵ 8100 9

2.15 4.1823 6.57 × 10-5 10500 10

1.83 4.5036 3.14 × 10⁻⁵ 22000 11

1.29 5.3372 4.6 × 10⁻⁶ 150000 12

0.93* 5.82 1.5 × 10⁻⁶ 460000 13

2.34 3.77 0.000170 4053 14

2.14 4.19 6.45 × 10⁻⁵ 10700 15

3.2* 2.59 0.00259 266 16

2.1* 4.17 0.0000673 10300 17

3.15* 2.70 0.0020 346 18

2.5* 3.61 0.0002460 2818 †For example, pKa of the corresponding COOH toCompound 1 would be the pKa of the corresponding carboxylic acid

*= predicted by calculation

It has been reported that aryltrifluoroborates can be considerablystabilized by an electron-poor environment (see, for example, Ting etal. (2008, J. Org. Chem. 73; 4662-70). It has also been reported thatEWGs (electron withdrawing group) on the benzene ring can significantlyslow down hydrolysis, resulting in longer solvolytic half-lives. Asimilar correlation with such substituent effects is seen with regardsto the nitration of benzene or the solvolysis of substituted benzyltosylates. Without being bound by theory, a possible mechanistic reasonfor this effect was that pi-electrons in the aryl ring could delocalizeinto the empty p-orbital on boron thus promoting B—F bond dissociation.As such, a group that weakened this effect could result in greater B—Fbond stability. However, in contrast to aryltrifluoroborates, fororganotrifluoroborates, there may or may not be pi-overlap by anelectron withdrawing group and hence there is no reason a priori to havethought that electron withdrawing groups would have any effects on theB—F bond stability or to what extent they might have retardedsolvolysis.

The existence of any relationship between pk_(B—F) observed for aparticular alkyl moiety of the fluoridated organotrifluoroboratecompound and the pKa of a carboxylic acid conjugated to the same alkylmoiety was also investigated. The pKa values for the carboxylic acidsconjugated to the same alkyl moieties of the fluoridatedorganotrifluoroborates tabulated in Table 1 are also included in thesame table. For example, for comparison purposes with pk_(B—F) forCompound 1 of Table 1, the pKa of the carboxylic acid

is also listed in Table 1. pk_(B—F) values for a number of fluoridatedorganotrifluoroborates were plotted as a function of the pKa values forthe corresponding carboxylic acids as shown in FIG. 2. Unexpectedly, asimple yet previously unknown relationship was observed between pKa andpk_(B—F) as seen in FIG. 2, i.e. that the log of the pseudo-first ordersolvolytic rate constant, log k_(solv.)(B—F), of RBF₃ is correlated tothe pKa of the corresponding carboxylic acid RCOOH (R=0.99) with a slopeof ˜−1.4. Without being bound by theory, one possible explanation forthis relationship could involve consideration of the impact of varioussubstituents on the electronic environment experienced by the carboxylicacid and in turn, the impact of the various substituent groups on thedissociability of the carboxylic acid proton. The observation of arelationship between the pKa and pk_(B—F) values also provides, in turn,an unexpected relationship between the pKa values and the stability orhalf-life of the fluoridated organotrifluoroborate compounds in terms ofsolvolytic defluoridation. A pKa of 2.85 or lower for the correspondingCOOH may inform the design of organotrifluoroborate compositions withsolvolytic half-lives of about 1000 min or longer. The box provides anapproximate range that is indicative, although not determinative, ofpreferred utility.

This discovery now permits the stability of such organotrifluoroboratestructures to be predicted, such that candidates fororganoorganotrifluoroborates that will be useful in imaging may beselected and tested. A person skilled in the art of synthesis mayconsider the pKa of any carboxylic acid (with whatever modifications) bymeasurement or which is known (e.g. Jencks, Bordwell, CRC Handbook) orpredicted by computer simulation, and use this knowledge to contemplateand design alkyltrifluoroborate structures that would have sufficientlylong half-lives for use in the production of radiotracers.

Accordingly, a person skilled in the art may exploit this newlydiscovered relationship to identify candidate organotrifluoroboratecompounds that are most likely to be useful as imaging agents. However,the invention is in no way limited to compounds that follow thisrelationship. Even though certain useful nonaromatic substitutedoragnotrifluoroborate structures may deviate from this relationship whenconsidered based solely on the pKa of a corresponding carboxylic acid, aperson skilled in the art will understand that certain second ordereffects may dampen or accentuate the impact of various substituents onthe electronic environment. Such deviations may easily be understood interms of second-order effects related to steric interactions, to thepresence of a second ionizable or charged group, or to other constraintsthat become clear in light of this relationship. Moreover, thisrelationship may guide the person skilled in the art when consideringcompounds that have no corresponding carboxylic acid.

This relationship also allows an electron withdrawing group to be placedas close to the boron as the carbon to which the boron is attached,whereas the geometry of an aryl ring requires that any electronwithdrawing group be placed at least two carbon atoms away from theboron.

Example 4 Evaluation of Stability of ¹⁸F-Radiolabeled FluoridatedOrganotrifluoroboratesby Thin Layer Chromatography (TLC)

The following is a representative example of testing of solvolyticdefluoridation of a fluoridated organotrifluoroborateas shown in FIG. 3.2 nmol Rhodamine-BF₃ was added into 100 μL plasma, and then incubated at37° C. After 2 hours, 200 μL acetonitrile (ACN) was added to precipitatethe protein from the solution. The crude was filtered with 40 μm filterpaper, and then a reddish purple solution was achieved. 1 μL of thissolution was loaded on the TLC plate. The TLC plate was developed by 15%methanol/DCM. The TLC chromatograms for an aryltrifluoroborate(Rhodamine-ArBF₃), Rhodamine-PyrBF₃, and a quaternaryammoniomethyltrifluoroborate (Rhodamine-Compound 10 of Table 1) areshown as FIG. 3.

In the TLC chromatograms, Rhodamine B was conjugated with thetrifluoroborate to trace the decomposition. The hydrolyzed product lostthe negative charge, and therefore migrated much more rapidly than theprecursor. Based on the TLC chromatograms the ArBF₃ showed decompositionafter incubation in plasma for two hours. PyrBF₃ exhibited greaterstability than ArBF₃ because less decomposition was detected on the TLCchromatogram. Moreover, for Compound 10 of Table 1, almost no hydrolyzedproduct was detected based on the fluorescence analysis. The lack ofdetection of hydrolyzed product for Compound 10 of Table 1 suggests thatCompound 10 has extraordinary stability in plasma and may also showexcellent stability in animal models.

Example 4 Evaluation of Stability of ¹⁸F-radiolabeled FluoridatedOrganotrifluoroborates by High-performance Liquid Chromatography (HPLC)

1.1 mCi of ¹⁸F-Compound 10 (¹⁸F-ammoniomethyltrifluoroborate) was mixedwith 100 L of plasma to form a ¹⁸F-Compound 10-plasma mixture, and thenincubated at 37° C. for two hours. 200 uL of acetonitrile (ACN) was thenadded to the ¹⁸F-Compound 10-plasma mixture to precipitate the proteinfrom the mixture. The precipitated protein portion was separated fromthe mixture by filtration with 40 m filter paper, and the clear filtratewas injected into an HPLC for stability analysis. Chromatograms forindependent HPLC tests of Rhodamine-Compound 10 of Table 1 at 0 minutes(A), 80 minutes (B), 150 minutes (C), 0 minutes (D), 150 minutes (E),and 150 minutes (F) are shown in FIG. 4. Based on the in vitro test(n=3), almost no decomposition was observed in 150 mins, which provedthat Compound 10 has excellent stability in plasma. The observedexcellent stability of Compound 10 in plasma suggest that it shouldpresent good stability under in vivo conditions.

Example 5 Radiolabeling and Animal Study with Rhodamine(B)-AMBF₃

The following compound, wherein Rhodamine(B) is conjugated to Compound10, was synthesized and injected into mice.

Compound 18 was synthesized according to the method outlined below:

FIG. 5A shows HPLC traces of radioactivity in the plasma of a ratinjected with Compound 18 at 0, 80 and 150 min post injection. FIG. 5Bshows PET/CT images of the mouse at 10, 30, and 60 min post injection.

Example 7 Radiolabeling and Animal Study withBissulfo-Rhodamine(B)-AMBF₃

The following compound, wherein sulforhodamine(B) is conjugated toCompound 13, was synthesized and injected into mice.

FIG. 6A show the uptake value of different organs for Rhodamine-Compound10 at 60 min post injection into a mouse. FIG. 6B is a PET/CT image of amouse injected with Rhodamine-Compound 10 at 60 min post injection.

Example 7 Folate-ammoniomethylamino-BF₃

The following compound, Compound 10 conjugated to folic acid, has beensynthesized.

Compound 20 was synthesized according to the method outlined below:

Example 8 BisRGD-rho-AMBF₃

Various embodiments of the invention provide peptides or neurotracersconjugated to the positron-emitting organofluoroborate compoundsdescribed herein. A person skilled in the art will understand that thepositron-emitting organofluoroborate compounds described herein can beconjugated to a ligand (e.g. a peptide or a neurotracer) with affinityand specificity for a biomolecule of interest, provided that a suitablelinker is chosen such that the affinity of the ligand for thebiomolecule of interest is not reduced by not more than a factor of 100.Such compounds may serve as useful tracers.

For example, BisRGD-rho-AMBF₃ (Compound 21)_has been synthesizedaccording to the methods described in Zhibo Liu et al. MedChemComm 20145: 171-179 and Liu et al. Nucl. Med and Biology 2013 40: 841-849.Methods for conjugation may include use of an alkyne- or azide-linkedtri-substituted ammonium methyl-BF3 or disubstituted protonatedammonium-methyl-BF3 that is linked to the peptide by copper-catalyzed orstrain promoted cycloaddition reactions. A person skilled in the artwill understand that rhodamine is used for the purposes of screeningvarious RBF3 on TLC and for easily measuring the specific activity of atracer, and has also been used specifically to direct tracers forcardiac imaging. However, those skilled in the art will furtherunderstand that the rhodamine can be replaced with a peptide or otherligand to be imaged.

FIG. 7 shows PET-CT images of mice injected with Compound 21.

Although various embodiments of the invention are disclosed herein, manyadaptations and modifications may be made within the scope of theinvention in accordance with the common general knowledge of thoseskilled in this art. Such modifications include the substitution ofknown equivalents for any aspect of the invention in order to achievethe same result in substantially the same way. Numeric ranges areinclusive of the numbers defining the range. The word ‘comprising’ maybe used herein as an open-ended term, substantially equivalent to thephrase ‘including, but not limited to’, and the word ‘comprises’ has acorresponding meaning. As used herein, the singular forms ‘a’, ‘an’ and‘the’ include plural referents unless the context clearly dictatesotherwise. Thus, for example, reference to ‘a thing’ includes more thanone such thing. Citation of references herein may be not an admissionthat such references are prior art to the present invention.Publications, including patents and patent applications, cited in thisspecification are incorporated herein by reference as if each individualpublication were specifically and individually indicated to beincorporated by reference herein and as though fully set forth herein.The invention includes all embodiments and variations substantially ashereinbefore described and with reference to the examples and drawings.

1. A positron emitting compound or salt thereof, wherein the compound isof the formula I:

wherein: B is boron; A is a linear or branched C₁-C₁₅ alkyl group, alinear or branched C₁-C₁₅ alkenyl, group, a linear or branched C₁-C₁₅alkynyl group, or a C₃-C₁₈ non-aromatic cycloalkyl group, wherein eachof the C₁-C₁₅ alkyl group, the C₁-C₁₅ alkenyl, group, the C₁-C₁₅alkynyl, group, and the C₃-C₁₈ non-aromatic cycloalkyl group isunsubstituted or substituted and optionally includes at least oneheteroatom interposed between two carbon atoms of the carbon chain ofthe group, wherein each of the at least one heteroatom is independentlyselected from the group consisting of O, S, N and P; A is joined to Bthrough a carbon atom; each Y¹ is independently selected from the groupconsisting of R, ¹⁸F and ¹⁹F; n=1 or 2; Y² is selected from the groupconsisting of R², ¹⁸F and ¹⁹F; R¹ is a non-interfering substituent withregard to fluoridation of B; R² is a non-interfering substituent withregard to fluoridation of B; and at least one of (Y¹)_(n) and Y² is ¹⁸F;providing that A is selected such that the pK_(a) of H^(a) of an acid ofthe formula II:

is less than or equal to about 2.8.
 2. The positron emitting compound orsalt of claim 1, wherein when A is substituted at the carbon alpha tothe

group with a group that has a dissociable proton, the dissociable protonhas a pKa greater than about 9 and contributes to a net positive chargeon the group that has the dissociable proton.
 3. The positron emittingcompound or salt of claim 1 or 2, wherein A is selected such that thepK_(a) of H^(a) of the acid of the formula II is less than or equal toabout 2.4.
 4. The positron emitting compound or salt of claim 1 or 2,wherein A is selected such that the pK_(a) of H^(a) of the acid of theformula II is less than or equal to about 2.0.
 5. The positron emittingcompound or salt of claim 1 or 2, wherein A is selected such that thepK_(a) of H^(a) of the acid of formula II is less than or equal to about1.5.
 6. The positron emitting compound or salt of claim 1 or 2, whereinA is selected such that the pK_(a) of H^(a) of the acid of formula II isless than or equal to about 1.0.
 7. The positron emitting compound orsalt of any one of claims 1 to 6, wherein A is substituted with one ormore substituents independently selected from the group consisting of F,Cl, Br, I, —N⁺(C₁₋₁₅alkyl)₃, —N⁺(C₂₋₁₅alkenyl)₃, —N⁺(C₂₋₁₅alkynyl)₃,—N⁺H(C₁₋₁₅alkyl)₂, —N⁺H(C₂₋₁₅alkenyl)₂, —N⁺H(C₂₋₁₅alkynyl)₂,P⁺(C₁₋₁₅alkyl)₃, P⁺(C₂₋₁₅alkenyl)₃, P⁺(C₂₋₁₅alkynyl)₃, S⁺(C₁₋₁₅alkyl)₂,S⁺(C₂₋₁₅alkenyl)₂, S⁺(C₂₋₁₅alkynyl)₂, oxo (i.e., ═O), OH, —OC₁₋₁₅alkyl,unsubstituted or substituted aromatic C₃-C₁₈ cycloalkyl, unsubstitutedor substituted non-aromatic C₃-C₁₈ heterocyclic group, unsubstituted orsubstituted aromatic C₃-C₁₈ heterocyclic group, ═NH, —C₁-C₁₅alkyl,non-aromatic C₃-C₁₈ cycloalkyl, —N(C₁₋₁₅alkyl)₂, —N(C₂₋₁₅alkenyl)₂,—N(C₂₋₁₅alkynyl)₂, —COOH, —NH₂, —SH, a biomolecule, and a linking groupoptionally joined to a biomolecule.
 8. The positron emitting compound orsalt of any one of claims 1 to 7, wherein A is substituted with at leastone substituent that is a biomolecule or a linking group optionallyjoined to a biomolecule.
 9. The positron emitting compound or salt asdefined in any one of claims 1 to 8, wherein the compound is of theformula (IV):

wherein: Q¹ is —CR³R⁴R⁵, —C≡CR⁸,

or —R¹⁰C═CR¹¹R¹²; each of R³, R⁴, and R⁵ is independently H, D, F, Cl,Br, I, CX₃, —N⁺R¹⁵R¹⁶R¹⁷, —P⁺R¹⁸R¹⁹R²⁰, —S⁺R²¹R²², —NR²³R²⁴, NHR²³ abiomolecule, a linking group optionally joined to a biomolecule, alinear or branched C₁-C₁₅ alkyl group, or a C₃-C₁₈ cycloalkyl group,wherein each of the C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl groupis unsubstituted or substituted and is optionally includes at least oneheteroatom interposed between two carbon atoms of the carbon chain ofthe group, wherein each of the at least one heteroatom is independentlyselected from the group consisting of O, S, N and P, each of the C₁-C₁₅alkyl group and the C₃-C₁₈ cycloalkyl group is joined to the carbon atomof —CR³R⁴R⁵ through a carbon atom, and each X is the same or differentand is F, Cl, Br, or I; each of R¹⁵, R¹⁶ and R¹⁷ is independently H, D,a biomolecule, a linking group optionally joined to a biomolecule, alinear or branched C₁-C₁₅ alkyl group, or a C₃-C₁₈ cycloalkyl group,wherein each of the C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl groupis unsubstituted or substituted and optionally includes at least oneheteroatom interposed between two carbon atoms of the carbon chain ofthe group, wherein each of the at least one heteroatom is independentlyselected from the group consisting of O, S, N and P, and each of theC₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl group is joined to thenitrogen atom of —N⁺R¹⁵R¹⁶R¹⁷ through a carbon atom, or R¹⁵ is absentand R¹⁶ and R¹⁷ are joined so that —N⁺R¹⁵R¹⁶R¹⁷ forms a positivelycharged nitrogen containing heterocyclic group which is substituted orunsubstituted; each of R¹⁸, R¹⁹, and R²⁰ is independently H, D, abiomolecule, a linking group optionally joined to a biomolecule, alinear or branched C₁-C₁₅ alkyl group, or a C₃-C₁₈ cycloalkyl group,wherein each of the C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl groupis unsubstituted or substituted and includes at least one heteroatominterposed between two carbon atoms of the carbon chain of the group,wherein each of the at least one heteroatom is independently selectedfrom the group consisting of O, S, N and P, and each of the C₁-C₁₅ alkylgroup and the C₃-C₁₈ cycloalkyl group is joined to the phosphorus atomof —P⁺R¹⁸R¹⁹R²⁰ through a carbon atom; each of R²¹ and R²² isindependently H, D, a biomolecule, a linking group optionally joined toa biomolecule, a linear or branched C₁-C₁₅ alkyl group, or a C₃-C₁₈cycloalkyl group, wherein each of the C₁-C₁₅ alkyl group and the C₃-C₁₈cycloalkyl group is unsubstituted or substituted and optionally includesat least one heteroatom interposed between two carbon atoms of thecarbon chain of the group, wherein each of the at least one heteroatomis independently selected from the group consisting of O, S, N and P,and each of the C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl group isjoined to the sulfur atom of —S⁺R²¹R²² through a carbon atom; each ofR²³ and R²⁴ is independently H, D, a biomolecule, a linking groupoptionally joined to a biomolecule, a linear or branched C₁-C₁₅ alkylgroup, or a C₃-C₁₈ cycloalkyl group, wherein each of the C₁-C₁₅ alkylgroup and the C₃-C₁₈ cycloalkyl group is unsubstituted or substitutedand optionally includes at least one heteroatom interposed between twocarbon atoms of the carbon chain of the group, wherein each of the atleast one heteroatom is independently selected from the group consistingof O, S, N and P, and each of the C₁-C₁₅ alkyl group and the C₃-C₁₈cycloalkyl group is joined to the nitrogen atom of —NR²³R²⁴ through acarbon atom; R⁸ is —N⁺R²⁵R²⁶R²⁷, —P⁺R²⁸R²⁹R³⁰, —S⁺R³¹R³², —NR³³R³⁴,

a biomolecule, a linking group optionally joined to a biomolecule, alinear or branched C₁-C₁₅ alkyl group, or a C₃-C₁₈ cycloalkyl group,wherein each of the C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl groupis substituted with at least one substituent that is a biomolecule andoptionally includes at least one heteroatom interposed between twocarbon atoms of the carbon chain of the group, wherein each of the atleast one heteroatom is independently selected from the group consistingof O, S, N and P, and each of the C₁-C₁₅ alkyl group and the C₃-C₁₈cycloalkyl group is joined to the carbon atom of —C≡CR⁸ through a carbonatom; each of R²⁵, R²⁶ and R²⁷ is independently H, D, a biomolecule, alinking group optionally joined to a biomolecule, a linear or branchedC₁-C₁₅ alkyl group, or a C₃-C₁₈ cycloalkyl group, wherein each of theC₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl group is unsubstituted orsubstituted and optionally includes at least one heteroatom interposedbetween two carbon atoms of the carbon chain of the group, wherein eachof the at least one heteroatom is independently selected from the groupconsisting of O, S, N and P, and each of the C₁-C₁₅ alkyl group and theC₃-C₁₈ cycloalkyl group is joined to the nitrogen atom of —N⁺R²⁵R²⁶R²⁷through a carbon atom, or R²⁵ is absent and R²⁶ and R²⁷ are joined sothat —N⁺R²⁵R²⁶R²⁷ forms a positively charged nitrogen containingheterocyclic group which is unsubstituted or substituted; each of R²⁸,R²⁹, and R³⁰ is independently H, D, a biomolecule, a linking groupoptionally joined to a biomolecule, a linear or branched C₁-C₁₅ alkylgroup, or a C₃-C₁₈ cycloalkyl group, wherein each of the C₁-C₁₅ alkylgroup and the C₃-C₁₈ cycloalkyl group is unsubstituted or substitutedand optionally includes at least one heteroatom interposed between twocarbon atoms of the carbon chain of the group, wherein each of the atleast one heteroatom is independently selected from the group consistingof O, S, N and P, and each of the C₁-C₁₅ alkyl group and the C₃-C₁₈cycloalkyl group is joined to the phosphorus atom of —P⁺R²⁸R²⁹R³⁰through a carbon atom; each of R³¹ and R³² is independently H, D, abiomolecule, a linking group optionally joined to a biomolecule, alinear or branched C₁-C₁₅ alkyl group, or a C₃-C₁₈ cycloalkyl group,wherein each of the C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl groupis unsubstituted or substituted and optionally includes at least oneheteroatom interposed between two carbon atoms of the carbon chain ofthe group, wherein each of the at least one heteroatom is independentlyselected from the group consisting of O, S, N and P, and each of theC₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl group is joined to thesulfur atom of —S⁺R³¹R³² through a carbon atom; each of R³³ and R³⁴ isindependently H, D, a biomolecule, a linking group optionally joined toa biomolecule, a linear or branched C₁-C₁₅ alkyl group, or a C₃-C₁₈cycloalkyl group, wherein each of the C₁-C₁₅ alkyl group and the C₃-C₁₈cycloalkyl group is unsubstituted or substituted and optionally includesat least one heteroatom interposed between two carbon atoms of thecarbon chain of the group, wherein each of the at least one heteroatomis independently selected from the group consisting of O, S, N and P,and each of the C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl group isjoined to the nitrogen atom of —NR³³R³⁴ through a carbon atom; R³⁵ is abiomolecule, a linking group optionally joined to a biomolecule, alinear or branched C₁-C₁₅ alkyl group, or a C₃-C₁₈ cycloalkyl group,wherein each of the C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl groupis substituted with at least one substituent that is a biomolecule andoptionally includes at least one heteroatom interposed between twocarbon atoms of the carbon chain of the group, wherein each of the atleast one heteroatom is independently selected from the group consistingof O, S, N and P, and each of the C₁-C₁₅ alkyl group and the C₃-C₁₈cycloalkyl group is joined to the carbon atom of

through a carbon atom; R⁹ is —NR³⁸R³⁹,

a biomolecule, a linking group optionally joined to a biomolecule, alinear or branched C₁-C₁₅ alkyl group, or a C₃-C₁₈ cycloalkyl group,wherein each of the C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl groupis substituted with at least one substituent that is a biomolecule andoptionally includes at least one heteroatom interposed between twocarbon atoms of the carbon chain of the group, wherein each of the atleast one heteroatom is independently selected from the group consistingof O, S, N and P, and each of the C₁-C₁₅ alkyl group and the C₃-C₁₈cycloalkyl group is joined to the carbon atom of

through a carbon atom; each of R³⁸ and R³⁹ is independently H, D, abiomolecule, a linking group optionally joined to a biomolecule, alinear or branched C₁-C₁₅ alkyl group, or a C₃-C₁₈ cycloalkyl group,wherein each of the C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl groupis unsubstituted or substituted and optionally includes at least oneheteroatom interposed between two carbon atoms of the carbon chain ofthe group, wherein each of the at least one heteroatom is independentlyselected from the group consisting of O, S, N and P, and each of theC₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl group is joined to thenitrogen atom of —NR³⁸R³⁹ through a carbon atom; R⁴⁰ is a biomolecule, alinking group optionally joined to a biomolecule, a linear or branchedC₁-C₁₅ alkyl group, or a C₃-C₁₈ cycloalkyl group, wherein each of theC₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl group is substituted withat least one substituent that is a biomolecule and optionally includesat least one heteroatom interposed between two carbon atoms of thecarbon chain of the group, wherein each of the at least one heteroatomis independently selected from the group consisting of O, S, N and P,and each of the C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl group isjoined to the carbon atom of

through a carbon atom; each of R¹⁰, R¹¹, and R¹² is independently H, D,F, Cl, Br, I, CX₃, —N⁺R⁴¹R⁴²R⁴³, —P⁺R⁴⁴R⁴⁵R⁴⁶, —S⁺R⁴⁷R⁴⁸, a biomolecule,a linking group optionally joined to a biomolecule, a linear or branchedC₁-C₁₅ alkyl group, or a C₃-C₁₈ cycloalkyl group, wherein each of theC₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl group is unsubstituted orsubstituted and optionally includes at least one heteroatom interposedbetween two carbon atoms of the carbon chain of the group, wherein eachof the at least one heteroatom is independently selected from the groupconsisting of O, S, N and P, each of the C₁-C₁₅ alkyl group and theC₃-C₁₈ cycloalkyl group is joined to the carbon atom of —R¹⁰C═CR¹¹R¹²through a carbon atom, and each X is the same or different and is F, Cl,Br, or I; each of R⁴¹, R⁴² and R⁴³ is independently H, D, a biomolecule,a linking group optionally joined to a biomolecule, a linear or branchedC₁-C₁₅ alkyl group, or a C₃-C₁₈ cycloalkyl group, wherein each of theC₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl group is unsubstituted orsubstituted and optionally includes at least one heteroatom interposedbetween two carbon atoms of the carbon chain of the group, wherein eachof the at least one heteroatom is independently selected from the groupconsisting of O, S, N and P, and each of the C₁-C₁₅ alkyl group and theC₃-C₁₈ cycloalkyl group is joined to the nitrogen atom of —N⁺R⁴¹R⁴²R⁴³through a carbon atom, or R⁴¹ is absent and R⁴² and R⁴³ are joined sothat —N⁺R⁴¹R⁴²R⁴³ forms a positively charged nitrogen containingheterocyclic group which is substituted or unsubstituted; each of R⁴⁴,R⁴⁵, and R⁴⁶ is independently H, D, a biomolecule, a linking groupoptionally joined to a biomolecule, a linear or branched C₁-C₁₅ alkylgroup, or a C₃-C₁₈ cycloalkyl group, wherein each of the C₁-C₁₅ alkylgroup and the C₃-C₁₈ cycloalkyl group is unsubstituted or substitutedand optionally includes at least one heteroatom interposed between twocarbon atoms of the carbon chain of the group, wherein each of the atleast one heteroatom is independently selected from the group consistingof O, S, N and P, and each of the C₁-C₁₅ alkyl group and the C₃-C₁₈cycloalkyl group is joined to the phosphorus atom of —P⁺R⁴⁴R⁴⁵R⁴⁶through a carbon atom; each of R⁴⁷ and R⁴⁸ is independently H, D, abiomolecule, a linking group optionally joined to a biomolecule, alinear or branched C₁-C₁₅ alkyl group, or a C₃-C₁₈ cycloalkyl group,wherein each of the C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl groupis unsubstituted or substituted and optionally includes at least oneheteroatom interposed between two carbon atoms of the carbon chain ofthe group, wherein each of the at least one heteroatom is independentlyselected from the group consisting of O, S, N and P, and each of theC₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl group is joined to thesulfur atom of —S⁺R⁴⁷R⁴⁸ through a carbon atom; at least one of R³, R⁴,R⁵, R⁸, R⁹, R¹⁰, R¹¹, R¹², R¹⁵, R¹⁶, R¹⁷, R¹⁸, R¹⁹, R²⁰, R²¹, R²², R²³,R²⁴ R²⁵, R²⁶, R²⁷, R²⁸, R²⁹, R³⁰, R³¹, R³², R³³, R³⁴, R³⁵, R³⁸, R³⁹,R⁴⁰, R⁴¹, R⁴², R⁴³, R⁴⁴, R⁴⁵, R⁴⁶, R⁴⁷, and R⁴⁸ is a biomolecule, alinking group optionally joined to a biomolecule, or a group that issubstituted with at least one substituent that is a biomolecule, orforms a group that is substituted with at least one substituent that isa biomolecule; and B, Y¹, n and Y² are as defined in claim 1, providedthat when Q is —CR³R⁴R⁵, at least one of R³, R⁴ and R⁵ is F, Cl, Br, I,CX₃, —N⁺R¹⁵R¹⁶R¹⁷, —P⁺R¹⁸R¹⁹R²⁰, —S⁺R²¹R²² or NR²³R²⁴.
 10. The positronemitting compound or salt of claim 9, wherein Q¹ is —CR³R⁴R⁵,

or —R¹⁰C═CR¹¹R¹²; and each R³, R⁴, R⁵, R⁹, R¹⁰, R¹¹, and R¹² is asdefined in claim
 9. 11. The positron emitting compound or salt of claim9, wherein Q¹ is —CR³R⁴R⁵, —C≡CR⁸, or

and each of R³, R⁴, R⁵, R⁸, and R⁹ is as defined in claim
 9. 12. Thepositron emitting compound or salt of claim 9, wherein Q¹ is —CR³R⁴R⁵ or—C≡CR⁸; and each of R³, R⁴, R⁵, and R⁸ is as defined in claim
 9. 13. Thepositron emitting compound or salt of claim 9, wherein Q¹ is —CR³R⁴R⁵;and each of R³, R⁴, and R⁵ is as defined in claim
 9. 14. The positronemitting compound or salt of claim 9, wherein: Q¹ is —CR³R⁴R⁵; each ofR³, R⁴, and R⁵ is as defined in claim 9; at least two of R³, R⁴ and R⁵are independently F, Cl, Br, I, or CX₃, or at least one of R³, R⁴ and R⁵is —N⁺R¹⁵R¹⁶R¹⁷, —P⁺R¹⁸R¹⁹R²⁰, —S⁺R²¹R²², or NR²³R²⁴; each of R¹⁵, R¹⁶,R¹⁷, R¹⁸, R¹⁹, R²⁰, R²¹, R²², R²³, and R²⁴ is as defined in claim 9; andat least one of R³, R⁴, R⁵, R¹⁵, R¹⁶, R¹⁷, R¹⁸, R¹⁹, R²⁰, R²¹, R²², R²³,and R²⁴ is a biomolecule, a linking group optionally joined to abiomolecule, or a group that is substituted with at least onesubstituent that is a biomolecule, or forms a group that is substitutedwith at least one substituent that is a biomolecule.
 15. The positronemitting compound or salt of claim 9, wherein: Q¹ is —CR³R⁴R⁵; each ofR³, R⁴, and R⁵ are selected from H, D, F, Cl, Br, I, CX₃, —N⁺R¹⁵R¹⁶R¹⁷,a biomolecule, a linking group optionally joined to a biomolecule, alinear or branched C₁-C₁₅ alkyl group, and a C₃-C₁₈ cycloalkyl group,wherein each of the C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl groupis unsubstituted or substituted and optionally includes at least oneheteroatom interposed between two carbon atoms of the carbon chain ofthe group, wherein each of the at least one heteroatom is independentlyselected from the group consisting of O, S, N and P, each of the C₁-C₁₅alkyl group and the C₃-C₁₈ cycloalkyl group is joined to the carbon atomof —CR³R⁴R⁵ through a carbon atom, and each X is the same or differentand is F, Cl, Br, or I; each of R¹⁵, R¹⁶ and R¹⁷ is as defined in claim9; at least two of R³, R⁴ and R⁵ are independently F, Cl, Br, I, or CX₃,or at least one of R³, R⁴ and R⁵ is —N⁺R¹⁵R¹⁶R¹⁷; and at least one ofR³, R⁴, R⁵, R¹⁵, R¹⁶ and R¹⁷ is a biomolecule, a linking groupoptionally joined to a biomolecule, or a group that is substituted withat least one substituent that is a biomolecule, or forms a group that issubstituted with at least one substituent that is a biomolecule.
 16. Thepositron emitting compound or salt of claim 9, wherein: Q¹ is —CR³R⁴R⁵;each of R³, R⁴, and R⁵ are selected from F, Cl, Br, I, CX₃, abiomolecule, a linking group optionally joined to a biomolecule, alinear or branched C₁-C₁₅ alkyl group, and a C₃-C₁₈ cycloalkyl group,wherein each of the C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl groupis unsubstituted or substituted and optionally includes at least oneheteroatom interposed between two carbon atoms of the carbon chain ofthe group, wherein each of the at least one heteroatom is independentlyselected from the group consisting of O, S, N and P, each of the C₁-C₁₅alkyl group and the C₃-C₁₈ cycloalkyl group is joined to the carbon atomof —CR³R⁴R⁵ through a carbon atom, and each X is the same or differentand is F, Cl, Br, or I; two of R³, R⁴ and R⁵ are independently F, Cl,Br, I, or CX₃; and one of R³, R⁴ and R⁵ is a biomolecule, a linkinggroup optionally joined to a biomolecule, or is a group that issubstituted with at least one substituent that is a biomolecule.
 17. Thepositron emitting compound or salt of claim 9, wherein: Q¹ is —CR³R⁴R⁵;each of R³ and R⁴ is independently F or Cl; R⁵ a biomolecule, a linkinggroup optionally joined to a biomolecule, a linear or branched C₁-C₁₅alkyl group, or a C₃-C₁₈ cycloalkyl group, wherein each of the C₁-C₁₅alkyl group and the C₃-C₁₈ cycloalkyl group is substituted with at leastone substituent that is a biomolecule and optionally includes at leastone heteroatom interposed between two carbon atoms of the carbon chainof the group, wherein each of the at least one heteroatom isindependently selected from the group consisting of O, S, N and P, andeach of the C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl group is joinedto the carbon atom of —CR³R⁴R⁵ through a carbon atom.
 18. The positronemitting compound or salt of claim 9, wherein: Q¹ is —CR³R⁴R⁵; R³ is—N⁺R¹⁵R¹⁶R¹⁷; each of each of R⁴ and R⁵ is independently are selectedfrom H, D, a biomolecule, a linking group optionally joined to abiomolecule, a linear or branched C₁-C₁₅ alkyl group, or a C₃-C₁₈cycloalkyl group, wherein each of the C₁-C₁₅ alkyl group and the C₃-C₁₈cycloalkyl group is unsubstituted or substituted and optionally includesat least one heteroatom interposed between two carbon atoms of thecarbon chain of the group, wherein each of the at least one heteroatomis independently selected from the group consisting of O, S, N and P,and each of the C₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl group isjoined to the carbon atom of —CR³R⁴R⁵ through a carbon atom; each ofR¹⁵, R¹⁶ and R¹⁷ is independently H, D, a biomolecule, a linking groupoptionally joined to a biomolecule, a linear or branched C₁-C₁₅ alkylgroup, or a C₃-C₁₈ cycloalkyl group, wherein each of the C₁-C₁₅ alkylgroup and the C₃-C₁₈ cycloalkyl group is unsubstituted or substitutedand optionally includes at least one heteroatom interposed between twocarbon atoms of the carbon chain of the group, wherein each of the atleast one heteroatom is independently selected from the group consistingof O, S, N and P, and each of the C₁-C₁₅ alkyl group and the C₃-C₁₈cycloalkyl group is joined to the nitrogen atom of —N⁺R¹⁵R¹⁶R¹⁷ througha carbon atom, or R¹⁵ is absent and R¹⁶ and R¹⁷ are joined so that—N⁺R¹⁵R¹⁶R¹⁷ forms a positively charged nitrogen containing heterocyclicgroup which is substituted or unsubstituted; and at least one of R⁴, R⁵,R¹⁵, R¹⁶ and R¹⁷ is a biomolecule, a linking group optionally joined toa biomolecule, or a group that is substituted with at least onesubstituent that is a biomolecule, or forms a group that is substitutedwith at least one substituent that is a biomolecule.
 19. The positronemitting compound or salt of claim 9, wherein: Q¹ is —CR³R⁴R⁵; R³ is—N⁺R¹⁵R¹⁶R¹⁷; each of R⁴ and R⁵ is independently H, D, a biomolecule, ora linking group optionally joined to a biomolecule; each of R¹⁵, R¹⁶ andR¹⁷ is independently H, D, a biomolecule, a linking group optionallyjoined to a biomolecule, or a linear or branched C₁-C₆ alkyl group whichis unsubstituted or substituted, or R¹⁵ is absent and R¹⁶ and R¹⁷ arejoined so that —N⁺R¹⁵R¹⁶R¹⁷ forms a positively charged nitrogencontaining C₄-C₆ heterocyclic group which is substituted orunsubstituted; and at least one of R⁴, R⁵, R¹⁵, R¹⁶ and R¹⁷ is abiomolecule, a linking group optionally joined to a biomolecule, or agroup that is substituted with at least one substituent that is abiomolecule, or forms a group that is substituted with at least onesubstituent that is a biomolecule.
 20. The positron emitting compound orsalt of claim 9, wherein Q¹ is —C≡CR⁸; and R⁸ is as defined in claim 9.21. The positron emitting compound or salt of claim 9, wherein: Q¹ is—C≡CR⁸; R⁸ is a biomolecule, a linking group optionally joined to abiomolecule, a linear or branched C₁-C₁₅ alkyl group, or a C₃-C₁₈cycloalkyl group, wherein each of the C₁-C₁₅ alkyl group and the C₃-C₁₈cycloalkyl group is substituted with at least one substituent that is abiomolecule and is optionally intercepted with at least one heteroatomselected from the group consisting of O, S, N and P, and each of theC₁-C₁₅ alkyl group and the C₃-C₁₈ cycloalkyl group is joined to thecarbon atom of —C≡CR⁸ through a carbon atom.
 22. The positron emittingcompound or salt of claim 9, wherein Q¹ is

and R⁹ is as defined in claim
 8. 23. The positron emitting compound orsalt of claim 8, wherein Q¹ is —R¹⁰C═CR¹¹R¹²; and each of R¹⁰, R¹¹, andR¹² is as defined in claim
 9. 24. The positron emitting compound or saltof claim 1 or 2, wherein A is:


25. The positron emitting compound or salt of any one of claims 1 to 23,wherein each of R¹ and R² is independently a linear or branched C₁-C₁₅alkyl group or a non-aromatic C₃-C₁₈ cycloalkyl group, wherein each ofthe C₁-C₁₅ alkyl group and the non-aromatic C₃-C₁₈ cycloalkyl group isunsubstituted or substituted and is optionally intercepted with at leastone heteroatom selected from the group consisting of O, S, N and P. 26.A positron emitting compound or salt of any one of claims 1 to 25,wherein n is 2, each Y¹ is F and Y² is F.
 27. A positron emittingcompound or salt as defined in any one of claims 1 to 25, wherein atleast one of (Y¹)_(n) and Y² is ¹⁸F.
 28. A positron emitting compound orsalt as defined in any one of claims 1 to 27, having a solvolyticde-18F-fluoridation half-life at physiological pH of about 1000 minutesor more.
 29. A positron emitting compound or salt as defined in any oneof claims 1 to 27, having a solvolytic de-18F-fluoridation half-life atphysiological pH of about 5000 minutes or more.
 30. A positron emittingcompound or salt as defined in any one of claims 1 to 26, having asolvolytic de-18F-fluoridation half-life at physiological pH of about10000 minutes or more.
 31. A positron emitting compound or salt asdefined in any one of claims 1 to 27, having a solvolyticde-18F-fluoridation half-life at physiological pH of about 15000 minutesor more.
 32. A positron emitting compound or salt as defined in any oneof claims 1 to 27, having a solvolytic de-18F-fluoridation half-life atphysiological pH of about 20000 minutes or more.
 33. A positron emittingcompound or salt as defined in any one of claims 1 to 27, having asolvolytic de-18F-fluoridation half-life at physiological pH of about25000 minutes or more.
 34. A positron emitting compound or salt asdefined in any one of claims 1 to 27, having a solvolyticde-18F-fluoridation half-life at physiological pH of about 50000 minutesor more.
 35. A positron emitting compound or salt as defined in any oneof claims 1 to 27, having a solvolytic de-18F-fluoridation half-life atphysiological pH of about 100000 minutes or more.
 36. A positronemitting compound or salt as defined in any one of claims 1 to 27,having a solvolytic de-18F-fluoridation half-life at physiological pH ofabout 125000 minutes or more.
 37. A positron emitting compound or saltas defined in any one of claims 1 to 27, having a solvolyticde-18F-fluoridation half-life at physiological pH of about 150000minutes or more.
 38. A method of making a positron emitting compound orsalt as defined in claim 1, comprising contacting an ¹⁸F source with acompound or salt thereof, wherein the compound is of the formula I:

wherein: B is boron; A is a linear or branched C₁-C₁₅ alkyl group, alinear or branched C₁-C₁₅ alkenyl, group, a linear or branched C₁-C₁₅alkynyl group, or a C₃-C₁₈ non-aromatic cycloalkyl group, wherein eachof the C₁-C₁₅ alkyl group, the linear or branched C₁-C₁₅ alkenyl group,the linear or branched C₁-C₁₅ alkynyl group, and the C₃-C₁₈ non-aromaticcycloalkyl group is unsubstituted or substituted and optionally includesat least one heteroatom interposed between two carbon atoms of thecarbon chain of the group, wherein each of the at least one heteroatomis independently selected from the group consisting of O, S, N and P; Ais joined to B through a carbon atom; n=1 or 2; each Y¹ is independentlyselected from the group consisting of R¹ and a leaving group that can bedisplaced by fluoride; Y² is selected from the group consisting of R²and a leaving group that can be displaced by fluoride; at least one of(Y¹)_(n) and Y² is said leaving group when n is 2; R¹ is anon-interfering substituent with regard to fluoridation of B; R² is anon-interfering substituent with regard to fluoridation of B; andproviding that A is selected such that the pK_(a) of H^(a) of an acid ofthe formula II:

is less than or equal to about 2.8.
 39. The method claim 38, whereinwhen A is substituted at a carbon alpha to the

group with a group that has a dissociable proton, the dissociable protonhas a pKa greater than about 9 and contributes to a net positive chargeon the group that has the dissociable proton.
 40. The method of claim 38or 39, comprising, prior to contacting the compound or salt thereof withthe ¹⁸F source, selecting the compound on the basis that the pK_(a) ofH^(a) of an acid of the formula II:

is less than or equal to about 2.8.
 41. The method of claim 38, 39, or40 wherein said ¹⁸F source is a fluoride.
 42. The method of any one ofclaims 38 to 41, wherein A is further substituted by a biomolecule, or alinking group optionally joined to a biomolecule.
 43. A method ofperforming PET imaging comprising administering an imaging effectiveamount of a positron emitting compound or salt according to any one ofclaims 1 to 35 to a subject or object to be subjected to PET.
 44. Amethod of selecting a PET imaging agent or precursor thereof havingresistance to solvolyticfluoridationde-18F-fluoridationde-18F-fluoridation at physiological pH,the method comprising: (i) providing one or more compounds or saltthereof wherein the compound is of the formula I:

wherein: B is boron; A is a linear or branched C₁-C₁₅ alkyl group, alinear or branched C₁-C₁₅ alkenyl, group, a linear or branched C₁-C₁₅alkynyl group, or a C₃-C₁₈ non-aromatic cycloalkyl group, wherein eachof the C₁-C₁₅ alkyl group, the linear or branched C₁-C₁₅ alkenyl group,the linear or branched C₁-C₁₅ alkynyl group, and the C₃-C₁₈ non-aromaticcycloalkyl group is unsubstituted or substituted and optionally includesat least one heteroatom interposed between two carbon atoms of thecarbon chain of the group, wherein each of the at least one heteroatomis independently selected from the group consisting of O, S, N and P; Ais joined to B through a carbon atom; each Y¹ is independently selectedfrom the group consisting of R, ¹⁸F and ¹⁹F; n=1 or 2; Y² is selectedfrom the group consisting of R², ¹⁸F and ¹⁹F; R¹ is a non-interferingsubstituent with regard to fluoridation of B; R² is a non-interferingsubstituent with regard to fluoridation of B; and at least one of(Y¹)_(n) and Y² is ¹⁸F; providing that A is selected such that thepK_(a) of H^(a) of an acid of the formula II:

is less than or equal to about 2.8; (ii) assessing the half-life of thepresence of the fluorine bound to B; and (iii) selecting a compound orcompounds having said half-life of about 1000 minutes or more as saidimaging agent or precursor thereof.
 45. The method of claim 45, whereinwhen A is substituted at the carbon alpha to the

group with a group that has a dissociable proton, the dissociable protonhas a pKa greater than about 9 and contributes to a net positive chargeon the group that has the dissociable proton.
 46. The method of claim 44or 45, wherein the solvolytic de-18F-fluoridation half-life atphysiological pH is about 1000 minutes or more.
 47. The method of claim44 or 45, wherein the solvolytic de-18F-fluoridation half-life atphysiological pH is about 5000 minutes or more.
 48. The method of claim44 or 45, wherein the solvolytic de-18F-fluoridation half-life atphysiological pH is about 10000 minutes or more.
 49. The method of claim44 or 45, wherein the solvolytic de-18F-fluoridation half-life atphysiological pH is about 15000 minutes or more.
 50. The method of claim44 or 45, wherein the solvolytic de-18F-fluoridation half-life atphysiological pH is about 20000 minutes or more.
 51. The method of claim44 or 45, wherein the solvolytic de-18F-fluoridation half-life atphysiological pH is about 25000 minutes or more.
 52. The method of claim44 or 45, wherein the solvolytic de-18F-fluoridation half-life atphysiological pH is about 50000 minutes or more.
 53. The method of claim44 or 45, wherein the solvolytic de-18F-fluoridation half-life atphysiological pH is about 100000 minutes or more.
 54. The method ofclaim 44 or 45, wherein the solvolytic de-18F-fluoridation half-life atphysiological pH is about 125000 minutes or more.
 55. The method ofclaim 44 or 45, wherein the solvolytic de-18F-fluoridation half-life atphysiological pH of about 150000 minutes or more.
 56. The method of anyone of claims 44 to 55, wherein said fluorine comprises ¹⁸F.
 57. Themethod of any one of claims 44 to 56, wherein said selected compound orcompounds are for use as a whole body PET imaging agent or precursorthereof.
 58. A positron emitting compound or salt thereof as defined inany one of claims 1 to 37 for use as a whole body PET imaging agent orprecursor thereof.
 59. Use of a compound or salt thereof as a precursorin the manufacture of an ¹⁸F containing PET imaging agent, wherein thecompound is of the formula I:

wherein: B is boron; A is a linear or branched C₁-C₁₅ alkyl, a linear orbranched C₁-C₁₅ alkenyl group, a linear or branched C₁-C₁₅ alkynylgroup, or a C₃-C₁₈ non-aromatic cycloalkyl group, wherein each of theC₁-C₁₅ alkyl group, the linear or branched C₁-C₁₅ alkenyl group, thelinear or branched C₁-C₁₅ alkynyl group, and the C₃-C₁₈ non-aromaticcycloalkyl group is unsubstituted or substituted and optionally includesat least one heteroatom interposed between two carbon atoms of thecarbon chain of the group, wherein each of the at least one heteroatomis independently selected from the group consisting of O, S, N and P; Ais joined to B through a carbon atom; n=1 or 2; each Y¹ is independentlyselected from the group consisting of R¹ and a leaving group that can bedisplaced by ¹⁸F-fluoride; Y² is selected from the group consisting ofR² and a leaving group that can be displaced by ¹⁸F-fluoride; at leastone of (Y¹)_(n) and Y² is said leaving group when n is 2; R¹ is anon-interfering substituent with regard to fluoridation of B; R² is anon-interfering substituent with regard to fluoridation of B; andproviding that A is selected such that the pK_(a) of H^(a) of an acid ofthe formula II:

is less than or equal to about 2.8.
 60. The use of claim 59, whereinwhen A is substituted at a carbon alpha to the

group with a group that has a dissociable proton, the dissociable protonhas a pKa greater than about 9 and contributes to a net positive chargeon the group that has the dissociable proton.
 61. The use of claim 59 or60, wherein at least one leaving group is 19F.
 62. A conjugate or a saltthereof, wherein the conjugate comprises a peptide conjugated to apositron-emitting compound as defined in any one of claims 1 to 37.